The    Structure   and    Life-History 

of  the 

Hay-Scented    Fern. 


BY 


HENRY   SHOEMAKER   CONARD,  PH.  D. 


WASHINGTON,  D.  C. 

PUBLISHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON. 

1908. 


The    Structure   and    Life-History 

of  the 

Hay-Scented    Fern. 


BY 


HENRY    SHOEMAKER   CONARD,  PH.  D. 


WASHINGTON,  D.  C. 

PUBLISHED  BY  THE  CARNEGIE  INSTITUTION  OF  WASHINGTON. 

1908. 


CARNEGIE  INSTITUTION  OF  WASHINGTON 
PUBLICATION  No.  94 


THE   COHNMAN    PRINTING   CO. 
CARLISLE,    PA. 


C7 

PREFACE. 


Aside  from  certain  personal  interests  and  opinions,  the  impulse  to  the 
present  investigation  came  from  a  study  of  recent  papers  by  Jeffrey,  Boodle, 
and  Gwynne-Vaughan.  But  since  we  shall  never  know  the  true  relations 
of  a  plant  to  its  surrounding's  until  we  have  worked  out  its  complete  life- 
history,  it  seemed  to  me  very  desirable  to  have  all  of  our  knowledge  of 
this  species  collected  into  a  unit .  Therefore  the  study  was  carried  beyond 
the  problems  suggested  by  the  papers  referred  to. 

The  work  was  begun  in  odd  moments  of  an  instructorship  at  the  Uni- 
versity of  Pennsylvania,  but  nearly  all  of  it  was  actually  done  in  the 
Botanical  Laboratory  of  the  Johns  Hopkins  University,  and  this  paper  is  to 
be  regarded  as  Contribution  No.  7  from  that  Laboratory.  I  was  there  as 
' 'James  Buchanan  Johnston  Scholar"  from  February,  1905,  until  June, 
1906.  For  the  opportunity  to  carry  on  this  investigation  in  a  peculiarly 
stimulating  atmosphere,  I  am  deeply  indebted  to  those  who  administer 
the  affairs  of  the  university.  It  is  an  especial  pleasure  to  express  appre- 
ciation of  the  constant  friendly  interest  taken  by  Prof.  Duncan  S.  Johnson. 
The  fundamental  teachings  of  Prof.  W.  K.  Brooks  have  also  molded  many 
of  my  thoughts  and  expressions.  Thanks  are  due  to  Mr.  I.  F.  Lewis  for  a 
collection  of  material  from  Long  Island;  to  the  late  Mr.  E.  R.  Heacock  for 
my  first  pot  of  prothallia  and  "sporelings;"  to  Dr.  C.  E.  Waters  for  infor- 
mation and  for  the  excellent  photographs,  plates  1  and  2;  to  Henry  Holt  & 
Co.  for  the  use  of  two  copyrighted  pictures;  to  Capt.  John  Donnell  Smith 
for  library  facilities;  to  Mr.  J.  D.  Thompson,  of  the  Library  of  Congress, 
and  Mr.  Joseph  H.  Painter  and  Mr.  W.  R.  Maxon,  of  the  United  States 
National  Museum,  for  looking  up  certain  papers  not  otherwise  accessible 
to  me;  and  to  the  officers  of  the  Academy  of  Natural  Sciences  of  Philadel- 
phia for  the  use  of  several  rare  old  books.  All  of  these  obligations  are  now 
gratefully  acknowledged. 

HENRY  S.  CONARD. 

GRINNELL,  IOWA,  April,  1907. 


THE  STRUCTURE  AND  LIFE-HISTORY  OF  THE  HAY-SCENTED  FERN. 


By  HENRY  SHOEMAKER  CONARD, 
Professor  of  Botany,  Iowa  College. 


HISTORICAL  INTRODUCTION. 

The  hay-scented  fern,  Dennstcedtia  punctilobula  (Michx.)  Moore  (= 
Dicksonia  punctilobula  Willd.)  first  appeared  in  botanical  literature  in  1803, 
when  it  was  described  by  Michatix  as  follows: 

\Nephrodium~\  punctilobulum.  N.  majusculum:  stipite  nudo,  ramis  pinnulisque  pu- 
bescentihus:  fronde  longa,  bipinnata;  pinnulis  decurrentibus,  subovali-oblongis,  semi  et 
ultra  pinnatifidis;  lobulis  oblonguisculi,  apice  2-4-dentatis,  singulis  unipunctiferis.  Obs.: 
Habitus  Polyp,  filicis  fceminas  Linn.  Hab.  in  Canada.  [A.  Michaux,  1803,  p.  268.] 

There  is  nothing-  in  the  text  to  indicate  that  this  is  a  new  species. 
Michaux'  s  genus  Nephrodium  was  extremely  far-reaching',  being:  defined 
in  these  words:  "fructibus  punctis  subreniformibus"  (p.  266).  Among 
the  species  are  N.  thelypteroides,  marginale,  filix-ftzmina,  and  dryopteris! 

Swartz  (1806)  placed  the  hay-scented  fern  in  the  genus  Aspidium,  in 
which  he  was  followed  by  Willdenow  (1810).  The  latter  writer,  both  in 
his  own  text  and  in  his  quotation  from  Michaux,  changes  the  spelling  of 
the  specific  name  to  punctilobum.  But  he  had  already  (1809)  described  it 
under  the  name  of  Dicksonia  pilosiuscula,  and  this,  too,  is  copied  in  the 
Species  Plantarum.  The  text  of  the  Enumeratio  (1809)  is  as  follows: 

DICKSONIA. 

Sort  subrotundi  distinct!  marginales.  Industum  duplex,  alterum  superficiarum  exte- 
rius  dehiscens,  alterum  e  margine  frondis  inflexo  interius  dehiscens. 


i. 

D.  frondibus  bipinnatis,  pinnis  pinnatifidis,  laciniis  dentatis,  rachi  pilosiuscula. 
Polypodium  pilosiusculum.     Miihlenberg  in  litt.     Habitat  in  Pennsylvania.     (!) 
Q[D. 

An  important  addition  to  the  other  diagnosis  is  the  notice  of  hairs  upon 
the  rachis.  These  are  so  characteristic  as  readily  to  distinguish  this  fern 
from  any  other  in  our  native  flora.  In  preparing  the  '  'Species'  '  ,  Willdenow 
recognized  the  similarity  of  his  Aspidium  punctilobum  and  Dicksonia  pilosius- 
cula as  expressed  in  the  closing  words  of  the  description  of  the  latter  : 

An  Aspidium  punctilobum  supra  p.  270  dubie  indicatum,  eadem  sit  filix  aliis  ad 
dijudicandum  relinquo?  quum  pinnulas  neque  sint  decurrentes  neque  pubescentes. 

5 


6  STRUCTURE   AND    LIFE-HISTORY   OF   HAY-SCENTED    FERN. 

Schkuhr  (1809,  p.  125,  plate  131)  referred  to  this  fern  as  Dicksonia 
bubescens*  He  has  been  followed  only  by  Presl  (1836,  p.  136). 

Desvaux  (1827)  made  this  species  the  type  and  only  member  of  his 
g-enus  Sitobolium.  His  diagnosis  of  the  genus  reads:  "Sori  globosi;  in- 
volucrum  fornicatum  globulosum  a  basi  ad  apicem  dehiscens"  (pp.  262, 
263).  No  specific  diagnosis  is  given. t  J.  Smith  (1841)  changed  the 
spelling1  to  Sitolobium,  and  Newman's  text  (1851)  gives  Litolobium.  G. 
Kunze  writes  thus  in  Linnaea  (23:249):  Sitobolium  (male  Sitolobium)," 
but  in  1848  the  printer  makes  him  say  "Litolobium  (not  Sitolobium)." 
Link's  (1841)  g-enus  Adectum\  is  too  late  ever  to  be  more  than  a  synonym. 
The  identity  of  the  plant,  however,  has  never  been  in  doubt,  for  it  stands 
absolutely  unique  amid  its  native  surroundings.  The  list  of  synonymy 
on  page  45  will  serve  to  show  how  the  name  has  been  bowled  about. 

Its  gfeneric  affinities  are  briefly  discussed  on  page  42.  We  will  simply 
state  that  its  place  is  at  present  established  in  Bernhardi's  (1800)  genus 
Dennst&dtia  (type:  D.flaccida=  Trichomanes  flaccidum  Forst.),  and  we 

*On  plate  131  marked  Dicksonia  pubescens.    Text  on  p.  125  reads: 

II.  DICKS.  ^pubescens  in  margin  of  page]  frondibus  subtripinnatis,  foliolis  lanceo- 
latis,  pinnis  oblongis,  laciniis  ovatis  dentatis,  stipite  glabro,  rachi  pubescente.  Sw. 
Mohr.  in  Litt. 

Nephr odium  punctilobuhim,  maiusculum;  stipite  nudo,  ramis  pinnulisque  pubescen- 
tibus:  fronde  longa,  bipinnata;  pinnulis  decurrentibus,  subovali-oblongis,  semi  et  ultra 
pinnatifidis;  lobulis  oblongiusculis,  apice  2-4-dentatis,  singulis  unipunctiferis.  Mich. 
Flor.  Bor.  Amer.  n.  p.  268. 

Habitat  in  Canada.     Habitus  Polypod.  filic.  fern.  Mich. 

Weichhaariger  Dicksonischer  Farn.  Mit  fast  3-mal  gefiedertem  Laube,  lanzet- 
fdrmigen  Blattern,  langlichen  Blattchen,  eyrunden,  gezahnten  Lappen,  glatten  Strunke 
und  eine  weichhaarigen  Spindel. 

Dieser  Farn  erhielt  ich  stiickweise  aus  Pennsylvanien  auch  unter  Polypodium  pilo- 
siusculum  Willd.,  wonach  ich  zwar  die  eigendliche  Grosse  nicht,  aber  nach  dessen 
Theilen  doch  die  3-fache  Fiederung  erkennen  kann.  .  .  .  [The  next  paragraph  de- 
scribes the  plate,  closing  with  the  words]  Alle  Rippen  der  Blattchen  and  Lappen  sind, 
wie  die  Spindel,  mit  gegliederten  Haaren  bekleidet. 
tDesvaux's  full  text  reads: 

SITOBOLIUM  N.  Sori  globosi;  involucrum  fornicatum  globulosum  a  basi  ad  apicem 
dehiscens. 

i.  S.  punctilobum  N.  Nephrodium  punctilobum  Mich.,  Fl.  am.  bor.,  n,  p.  268. 
Aspid.  punctilobum  Sw.,  Syn.t  p.  60.  Dicksonia  pilosiuscula  Willd.,  En.  hort.  ber.,  p. 
1076.  Dickson.  pubescens  Schk.,  Fil.,  t.  131. 

J  Link's  full  text  is  as  follows: 

ADECTUM. 

Frons  tripinnatisecta.  Sori  subrotundi  marginales  ad  sinus  frondis.  Indusium 
undique  ad  sorum  adnatum  eumque  tegens,  demum  medio  dehiscens  et  circulare. 

A.  Dicksonia  defectu  sporidochii  valde  differt. 

i.  A.pilosiusculumiv.  tripinnatifida,  pinnellis  brevibus,  antice  et  superne  incisis, 
stipite  rhachi  costisque  pubescentibus. 

D.  Fr.  1-2  ped.  alta,  pinnae  3  poll.  Igae.,  pinnulae  3  lin.  Igae. 

Dicksonia  pilosiuscula  W.  sp.  484.  W.  E.  1076.  ^.^.2.464.  H.  b.  2.10.  Raddi 
bras.  63.  Dicksonia  pubescens  Schkuhr  kr.  125  /.  132. 

Hab.  in  sylvis  opacis  ad  rupes  Pennsylvaniae  et  Virginiae  nee  non  in  locis  montosis 
prope  Tejuco  Brisiliae.  Perenne.  [p.  72.] 


HISTORICAL   INTRODUCTION.  7 

follow  Moore  (1857)  and  most  recent  scholars  in  accepting-  the  name  Denn- 
stcedtia  punctilobula  (Michx.)  Moore. 

Two  varieties  of  D.  punctilobula  have  been  described  in  recent  years. 
Dennst&dtia  punctilobula  var.  cristata  Maxon  (1899)  was  found  in  Massa- 
chusetts by  F.  G.  Floyd.  Under  cultivation  the  percentage  of  crested 
fronds  produced  varies  greatly.  "Some  fronds  have  not  only  had  the 
apex  of  every  pinna  doubly  or  trebly  crested,  but  the  apex  of  the  frond 
itself  has  frequently  been  bifidly  divided  with  heavily  crested  apices" 
(Davenport,  1905) .  I  have  several  times  seen  fronds  with  the  rachis  bifur- 
cated 10  cm.  or  more  below  the  apex.  Each  fork,  then,  bears  a  normal 
continuation  of  the  leaf.  Waters  (1903)  considers  this  condition  "fre- 
quent." He  also  states  (p.  289)  that  "A  form  with  rather  narrow  fronds, 
the  pinnae  unequal  in  length  and  with  the  teeth  of  the  ultimate  segments 
very  deeply  cut,  so  that  each  vein  forms  the  midrib  of  a  narrow  tongue- 
like  segment,  has  been  named  D.  pilosiuscula  schizophylla. ' '  Of  course  this 
name  should  read  Dennsttedtia  punctilobula  schizophylla.  On  the  relation 
of  these  varieties  to  the  typical  form  I  have  no  opinion  to  express. 

In  botanical  literature  other  than  taxonomic  or  noristic  the  hay-scented 
fern  scarcely  appears.  Descriptions  of  its  habit  of  growth,  its  glands,  and 
long,  slender  rhizome  are  given  by  Williamson  (1878,  p.  117,  plates  XLV, 
XLVI),  Eaton  (1879-1880,  pp.  341-343,  plate 44),  Clute  (1901,  pp.  225-231), 
and  Waters  (1903,  pp.  288-290).  Frances  Wilson  writes  an  appreciative 
general  account  of  these  features  in  the  Asa  Gray  Bulletin  (1897),  and 
Waters  (1903)  adds  to  a  pleasing  text  photographs  which  are  exquisite 
and  true  to  life.  Parsons  (1899)  and  Eastman  (1904)  refer  to  this  fern  in 
a  popular  way. 

Eaton  (1879-1880)  and  Waters  (1903)  speak  of  the  concentric  arrange- 
ment of  light  and  dark  tissues  in  the  rhizome  (cf.  fig.  67),  and  the  tax- 
onomic writers  tell  of  the  indusium  in  detail.  De  Bary  (1884)  describes 
the  vascular  bundle  of  Dennst&dtia  (naming  this  species  along  with  three 
others  in  parenthesis)  as  having  a  tubular  bundle,  "which  is  closed  as  far 
as  the  foliar  gap;  the  bundle  which  enters  the  leaf  arises  from  the  whole 
margin  of  the  gap  as  a  continuous  concave  plate  \_cf.  fig.  82],  which  is 
only  occasionally  split  up  at  its  base  into  several  bundles  lying  side  by 
side."  Gwynne-Vaughan  in  1901  (p.  85)  mentioned  the  present  species  as 
showing  thick- walled  elements  in  the  phloem  of  the  petiole.  In  1903 
(p.  691)  he  includes  D.  punctilobula  in  a  list  of  nineteen  ferns  with  typ- 
ical and  practically  identical  solenostelic  structure,  as  described  by  him 
in  Loxosoma  cunninghamii.  A  page  of  text  is  devoted  to  a  summary  of 
the  facts  of  structure  in  the  group.  A  summary  of  taxonomic  literature, 
with  synonymy,  is  given  on  our  pages  44  and  45  following. 


8  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

SPOROPHYTE. 

The  hay-scented  fern  occurs  generally  in  open  woods  (fig-,  l)  or  clear- 
ings or  on  roadside  banks.  It  prefers  well-drained,  stony  or  sandy  soil, 
and  usually  forms  thick  beds.  In  the  Catskill  Mountains  of  New  York 
and  in  New  England  it  grows  on  the  cleared  hillsides  in  dense  patches  8 
to  15  m.  in  diameter.  Its  range  is  from  New  Brunswick  to  Alabama  and 
Minnesota  (Britton  and  Brown,  1896,  1  :12).  The  leaves  are  from  50  to  90 
cm.  high,  lanceolate,  and  thrice  pinnatifid.  A  light-green  color  and  dense 
pubescence  combine  to  give  the  fern  a  soft,  feathery  appearance.  The 
glandular  hairs  exhale  a  delicate  fragrance  when  brushed,  which  has  been 
likened  to  new-mown  hay;  hence  the  common  name.*  The  stems  are  found 
5  to  15  cm.  beneath  the  surface  of  the  soil — long,  slender,  much-branching 
rhizomes  (fig.  3).  These  spread  rapidly  from  year  to  year,  and  give  rise 
to  the  densely  matted  beds  of  the  fern.  Roots  of  threadlike  fineness  arise 
plentifully  from  all  parts  of  the  rhizomes  and  ramify  through  the  soil. 

THE  ROOT. 

The  roots  are  numerous,  cylindrical,  with  copious,  two-ranked  branching. 
They  extend  more  horizontally  than  vertically  in  the  soil,  and  do  not  descend 
below  20  cm.  from  the  surface.  The  color  is  black  in  mature  portions, 
shading  in  the  younger  parts  through  reddish-brown  and  brownish -yellow 
to  creamy  white  at  the  apex.  Although  but  0.5  mm.  in  diameter  (maximum 
0.545  mm.;  minimum  0.49  mm.;  average  0.523  mm.),  they  are  tough  and 
wiry  in  texture.  The  rootlets  (secondary  roots)  are  about  half  as  thick  as 
the  main  roots.  Tertiary  roots,  similar  to  the  secondary,  frequently  occur. 
Only  rarely  does  a  root  arise  from  the  base  of  a  leaf,  and  then  it  is  usually 
within  4  mm.  of  the  center  of  the  rhizome. 

TABLE  i. — Acropetal  development  of  roots  from  stem. 


Length 
of  root. 

Distance 
from  apex 
of  stem. 

Branching. 

Collected. 

mm. 

mm. 

32 

No  branches          

Univ.  of  Pa.,  8/6/'o4. 

4-77 
6  40 

.  & 
32 

No  branches    ....            •• 

Fallsington,  Pa.,  io/4/'o3. 

3-2 

4  78 

.  ^ 

4-5 
6  40 

One  branch  4.7  mm.  long,  i 
cm.  from   stem. 
Many  branches       ....      

Do. 
Do. 

From  any  part  of  the  stem  roots  may  come  out,  but  more  frequently 
from  the  lower  side.  A  stem  5  cm.  long,  including  the  tip,  showed  eleven 
roots,  inserted  as  shown  in  fig.  9.  They  arise  in  acropetal  succession  very 


*The  names  fine-haired  fern,  mountain  fern,  gossamer  fern,  and  hairy  Dicksonia  are 
given  by  Clute  (1901,  p.  231),  and  sweet  grass  fern  by  Eastman  (1904,  p.  67). 


vSPOROPHYTE. 


near  to  the  stem  apex  (see  table  l)  and  lengthen  rapidly.  I  have  one 
which  is  24.5  cm.  long  and  the  broken  ends  were  frequently  found  at  a 
distance  of  20  cm.  from  the  stem.  It  is  likely  that  these  lengths  are  not 
much  exceeded.  The  rootlets  are  generally  alternate  on  opposite  sides  of 
the  primary  root-axis,  but  many  exceptions  occur.  Two  rootlets  are  often 
TABLE  2.  found  conseciitively  on  one  side,  and  in 

one  case  five  were  seen .  Successive  root- 
lets may  be  as  much  as  8  mm.  apart  or 
almost  or  quite  opposite  (figs.  6,  7,  8; 
table  2).  None  occur  usually  within  12 
or  15  mm.  of  the  stem. 

Table  2  shows  irregularities  in  alter- 
nate arrangement  of  rootlets  on  opposite 
sides  of  roots.  The  figures  indicate 
distance  in  millimeters  of  each  rootlet 
from  the  one  next  above  it,  and  columns 
show  alternation. 

The  root-cap  is  rather  long  and  pointed 
(fig.  23).  From  the  initial  cell  of  the 
root  outward  ten  rows  of  cells  may  be 
seen  in  a  strongly  developed  specimen, 
five  in  a  slender  root  of  a  sporeling. 
Outside  of  these  cell-layers  a  worn-out 
layer  is  seen,  in  the  act  of  sloughing  off . 
The  inner  layers  are  small-celled  and 
rich  in  protoplasm.  The  outermost  cells 
are  four  times  the  diameter  of  the  inner, 
but  still  nucleated .  Indeed ,  small ,  dense , 
nucleolus-like  nuclei  are  seen  even  in  the 
layer  that  is  shedding.  The  cap  thins 
out  layer  by  layer  along  the  sides  of  the 
root,  and  the  cells  become  very  long  and 
narrow.  The  outermost  layer  persists 
some  distance  above  the  next  inner  one. 
No  sign  of  statolith  bodies  has  been 
seen  in  any  part  of  the  root-cap. 

In  development,  each  terminal  segment  of  the  root-initial  gives  rise  to 
a  single  layer  of  root-cap  cells.*  The  segment  divides  first  by  an  anti- 
clinal wall  parallel  to  one  of  the  sides  of  the  initial  (figs.  10,  11,  26).  In 
successive  cap  segments  the  first  wall  of  one  stands  either  directly  over  or 
at  an  angle  of  60°  to  that  of  the  preceding  or  following  one,  and  not  at 


Root  1. 

Root  3. 

Right. 

Left. 

Right. 

Left. 

Stem 

Stem 

13-5 

13.0 

3-5 

3-5 

1.6 

2.0 

3-2 

2.0 

3-5 

I  .  $ 

1.8 

3-3 

3-5 

3-5 

3.O 

3  -° 

4.0 

1.5 

6.2 

8.0 

4.0 

3-3 

0.2 

4-5 

4.0 

6.5 

2.0 

3-5 

6-5 

Root  2. 

3-° 

4.0 

(?^ 

2.O 

/ 

4.0 

5-5 

6.0 

2-5 

3-5 

5.0 

0.5 

I  .  I 

3-0 

4.0 

3-3 

i-5 

Root  4. 

4.4 

6-5 

3-8 

(?) 

5  -° 

2-5 

1.6 

2.5 

6.5 

1.8 

5-0 

3.0 

8.0 

*In  a  few  cases  periclinal  walls  were  seen  in  three  to  five  or  six  of  the  median  cells, 
making  the  segment  two-layered  at  that  point  (fig.  24). 


10  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

45°,  as  stated  by  Nageli  and  Leitgeb  (1868,  p.  76).  The  halves  are  next 
cut  into  quadrants  by  anticlinals  at  right  angles  to  the  first  wall  (figs.  11, 
12,  25).  The  succeeding"  walls  in  the  quadrants  are  heterodromous  and 
may  be  parallel  to  either  of  the  preceding  or  be  oblique  (figs.  13,  25). 
No  further  regularity  was  found  in  the  division  of  root-cap  segments. 

The  initial  cell  of  the  root  is  a  triangular  pyramid  with  its  longest  axis 
in  the  axis  of  the  root  (figs.  23,  27,  28).  Lateral  segments  are  cut  off 
around  the  initial  on  one  side  after  another  in  regular  order.  I  noted  ten 
roots  (fig.  27)  in  which  the  succession  of  segments  was  counter-clockwise 
(proceeding  from  older  to  younger  segments)  and  four  in  which  it  was 
clockwise,  as  one  views  the  cell  from  its  outer  (cap ward)  base.  Each 
lateral  segment  divides  first  by  a  periclinal  wall  near  its  outer  margin 
(figs.  14,  15,  23,  27-29).  The  next  wall  is  a  radial  anticline  which  passes 
inward  from  near  the  middle  of  the  first,  and  strikes  one  of  the  sides  of 
the  segment  near  its  inner  angle,  dividing  the  inner  cell  into  "sextants" 
(fig.  16,  11;  segment  3  in  figs.  27-29).  Thus  there  is  in  each  segment  a 
larger  (major)  and  a  smaller  (minor)  sextant.  In  transverse  section  of 
the  root  we  see  the  three  major  sextants  meeting  at  the  center  of  the  sec- 
tion (figs.  29-33),  with  three  alternating  minor  sextants  which  do  not 
reach  quite  to  the  center.  The  "sextant  wall"  meets  that  side  of  the  seg- 
ment which  is  adjacent  to  the  next  older  segments,  (kathodic  wall)  and  is 
therefore  katadromous.  As  all  of  the  segments  in  any  root  are  alike  in 
this  respect,  the  divisions  are  said  to  be  homodromous.  Soon  after  the 
sextant  wall  is  formed  in  the  inner  part  of  the  segment  it  is  laid  down 
also  in  the  outer  part  (fig.  17;  segment  4  in  figs.  27-29). 

A  second  pericline  is  now  laid  down  near  the  middle  of  each  inner 
sextant  cell  (figs.  18^  23;  segment  5  in  figs.  27-30).  As  this  wall  forms 
the  boundary  between  the  plerome  and  outer  tissues,  it  may  be  called  the 
periplerome  wall.  Another  periclinal  laid  down  in  the  two  outer  sexants 
divides  these  into  two  layers,  the  definitive  epidermis  (piliferous  layer) 
and  hypodermis  (fig.  19;  segment  6  in  figs.  27-31).  Both  of  these  tissues 
remain  one-layered  throughout.  Subsequent  divisions  in  them  are  all 
anticlinal,  either  radial  or  transverse  (figs.  23;  27-33).  Almost  simul- 
taneously periclinal  walls  are  formed  on  each  side  of  the  periplerome  wall, 
near  and  parallel  to  it  (figs.  14,  20,  21,  walls  vi  and  vii;  23).  In  the 
majority  of  cases,  however,  the  outer  one  seems  to  precede.  The  result- 
ing cells  constitute  the  definitive  endodermis  and  pericycle.  The  cells  of 
the  former  are  from  the  beginning  flattened,  of  the  latter  nearly  cubical 
(figs.  23,  31,  33). 

If  we  group  the  segments  into  cycles  of  three ,  beginning  with  the  latest 
formed  (,cf.  figs.  27,  28),  we  find  walls  i  and  n  (figs.  14-22)  already  in  one 
or  more  of  the  youngest  cycle.  Walls  n,  in,  and  iv  are  found  in  the 
second  cycle,  and  vi  and  vii  in  the  second  or  third.  In  the  second  or 


SPOROPHYTE.  11 

third  cycle  of  segments  longitudinal  radial  anticlines  are  also  formed  in 
the  outer  members  of  the  segment,  dividing  the  sextants  into  halves  (figs. 
21,  22,  viu).  As  yet  each  segment  consists  of  but  one  layer  of  cells. 
Transverse  anticlines  occurring  throughout  the  segment  in  the  third  or 
fourth  cycle  make  it  two-layered  (fig.  23).  A  second  series  of  divisions 
in  the  same  plane  cuts  the  outer  tissues  (epidermis,  hypodermis,  cortex) 
into  four  vertical  layers.  These  cleavages  occur  first  in  the  epidermis, 
but  their  order  of  sequence  is  rapid  and  apparently  varied.  The  pericycle 
is  late  in  becoming  divided;  and  the  endodermis  of  a  certain  pair  of  oppo- 
site sextants  lacks  the  radial  division  for  a  long  time,  as  will  be  described 
in  speaking  of  the  origin  of  lateral  rootlets. 

The  large  cell  remaining  between  the  endodermis  and  hypodermis  (figs. 
14,  20,  21,  23)  gives  rise  to  all  of  the  cortex.  After  its  transverse  anti- 
clinal division  it  rapidly  undergoes  one  to  three  periclinal  and  as  many 
radial  divisions.  The  periclinals  probably  take  place  in  centrifugal  order. 
The  result  is  a  cortex  of  two  to  four  concentric  layers,  each  with  14  to  24 
cells.  The  last  divisions  are  complete  in  the  fourth,  or  at  least  the  fifth 
cycle  of  segments  {cf.  figs.  28-33). 

The  triangular  cells  lying  within  the  pericycle  (fig.  21)  divide  either 
by  a  periclinal  wall  into  two  parts  or  by  two  tangential  walls  into  three 
parts  (figs.  22,  29-31).  The  tips  of  the  three  major  sextants  and  of  one 
minor  (occasionally  two)  become  tracheids  of  the  metaxylem.  The  cells 
between  the  tracheids  and  the  pericycle  of  this  minor  and  of  the  major 
opposite  to  it  become  protoxylem  cells  (figs.  14,  22,  29-33);  the  inter- 
mediate parts  of  the  other  two  majors,  and  all  within  the  pericycle  in  the 
two  remaining  minors  (with  the  exception  noted  above)  go  to  form  phloem 
(figs.  14,  22,  29-33). 

As  the  elements  elongate,  the  transverse  limits  of  the  segments  are 
soon  obliterated  (fig.  23).  Four  or  at  most  five  cycles  only  can  be  recog- 
nized. The  sextants,  however,  may  often  be  distinguished  until  quite  a 
late  period  (fig.  33). 

The  above-described  order  of  the  early  divisions  of  the  segment  (walls 
i  to  vn,  figs.  14-22)  is  easily  followed  in  its  main  outlines  in  good  serial 
sections  of  any  leptosporangiate  fern  root.  But  English  and  German 
text-books*  still  adhere  unanimously  to  the  statement  of  Nageli  and 
Leitgeb  that  the  first  division  in  the  segment  is  the  sextant  wall,  fol- 
lowed by  that  which  separates  periblem  and  plerome.  The  first  error  was 
corrected  by  Lachmann  (1885;  18S7',Jide  Van  Tieghem  and  Douliot),  and 

*Nageli  and  Leitgeb,  1865,  1868;   Pteris        Campbell,  1895,  p.  328-329,  fig.  i65A ;  1905 

hastata,  plate  14,  fig.  7.  p.  333. 

Sachs,  1875,  pp.  124-125,  fig.  io2A.  Strasburger,  1897,  pp.  31 1-313,  figs.  139, 140. 

De  Bary,  1884,  pp.  18-19,  ^g8-  7Ai  8A-  Sadebeck,  1898,  p.  61,  fig.  4iA. 

Goebel,  1887,  pp.  214-215,  fig.  162.  Strasburger,  Noll,  etc.,  1898,  pp.  150-151, 
Bower,  1889.  fig.  165. 

Vines,  1894,  pp.  149-150,  figs.  114,  115-  Haberlandt,  1904,  p.  74,  fig.  14. 


12 


STRUCTURE    AND    LIFE-HISTORY    OF    HAY-SCENTED    FERN. 


the  second  by  Van  Teighem  and  Dotiliot  in  1888.  The  latter  authorities 
indicate  that  in  some  ferns  {Ptcris,  Adiantum,  Aneimia,  etc.)  the  outer 
cell  (figs.  14,  16,  17)  may  give  rise  to  two  or  three  layers  of  cortex  in  ad- 
dition to  the  epidermis  (see  table  of  cell-lineage  in  fern  roots,  p.  46).  Such 
ferns  are  in  the  minority.  The  same  writers  state  that  in  Rqnisetum, 
Osmunda,  and  Todea  the  first  periclinal  wall  is  between  the  central  cyl- 
inder and  cortex,  but  that  this  is  not  the  case  in  any  other  Pteridophytes 
which  have  a  single  initial  in  the  root. 

I  have  found  the  account  here  given  for  Dennstcedtia  as  to  the  origin  of 
epidermis,  hypodermis,  cortex,  and  endodermis  to  apply  equally  to  root-tips 
of  Cibotium  regale,  Aspidium  molle  (fig.  48),  Lygodium  japonicum,  Onoclea 
sensibilis  (fig.  51),  Ceratopteris  thalictroides  (fig.  50),  and  Aspidium  viar- 
ginale  (fig.  47).  In  Pteridium  aqnilinum  and  Didymockl&na  lunulata  (fig. 
49)  the  epidermis  and  two  layers  of  cortex  are  derived  from  the  same  part 
of  the  segment. 

Above  the  region  of  cell  division  in  the  root-tip  there  intervenes  a  brief 
region  of  elongation.  Beyond  this,  viz,  about  2.5  mm.  from  the  apex, 

root-hairs  appear.      Each  hair   is 

...    -,   .  ,1      /-          ^1  TABLE  3. — Root-hairs. 

a  cylindrical  outgrowth   from  the 

lower  (distal)  end  of  an  epidermal 

cell.  The  cavities  of  cell  and  hair  are 

continuous,   and  contain   but  one 

nucleus  (fig.  252)  lying  variously 

in    the  wall-layer   of   protoplasm. 

In  functional  hairs  the  nucleus  is 

seen  near  the  swollen  apex.     The 

walls  of  the  hairs  are  thin,  of  a  clear,  brownish-yellow  color,  and  are  often 

molded  around  irregular  particles  of  earth.      Table    3    gives  the  exact 

dimensions . 

A  transverse  section  of  the  region  of  functional  root-hairs  (figs.  34,  35, 
44)  shows  the  epidermis,  hypodermis,  four  or  five  (rarely  three)  layers  of 
cortex  and  a  well-defined  endodermis.  A  single  layer  (rarely  doubled  in 
places)  of  pericycle  surrounds  the  cylindrical,  diarch  bundle.  Protoxylems 
abut  directly  upon  the  pericycle  at  diametrically  opposite  points,  and 
between  them  lies  a  group  of  two  to  four  (rarely  five)  large  tracheids. 
Extending  around  within  the  pericycle  from  each  side  of  each  protoxylem 
is  a  row  of  three  to  seven  sieve-tubes.  Midway  between  the  protoxylems 
and  lying  against  the  pericycle  is  the  small-celled,  dense  protophloem. 
Between  the  phloem  and  xylem  are  cells  of  conjunctive  parenchyma. 

The  epidermis  (piliferous  layer  of  Van  Tieghem,  etc.)  at  the  level  we 
are  speaking  of  is  fully  mature,  and  consists  of  cells  four  to  six  times  as 
long  as  wide.  In  cross-section  they  are  nearly  isodiametric,  of  slightly 
variable  depth  and  width,  and  bulging  out  a  little  on  the  outer  side.  The 


Length. 

Diameter. 

Remarks. 

mm. 

mm. 

0-5+ 

0.014 

Broken  off. 

o.3+ 

0.014 

Do. 

O.2 

0.014 

Entire;  immature? 

SPOROPHYTE. 


13 


walls  are  brownish-yellow,  like  those  of  all  of  the  cells  outside  of  the 
endodermis.  The  subjacent  hypodermal  cells  are  about  three  times  as 
wide  and  twice  as  deep  radially  as  those  of  the  epidermis,  and  similarly 
elongated.  The  first  cortical  layer  is  composed  of  cells  nearly  twice  as 
larg-e  in  cross-section  as  the  foregoing,  but  like  the  last  in  length  and 
character  of  wall.  Intercellular  spaces  occur  rarely  at  the  angles  of  these 
cells.  The  cells  of  the  second  cortical  layer  are  smaller  again,  often  as 
narrow  as  the  epidermal  cells.  The  two  innermost  layers  are  still  smaller. 
In  the  last  three  layers,  especially  the  middle  one,  thickening  of  the  walls 
begins  even  before  the  root  hairs  are  fully  mature  (fig.  43).  At  this  stage 
the  endodermal  cells  are  already  very  long,  narrow,  and  practically  empty. 
Pericycle  and  conjunctive  parenchyma  are  full  of  dense,  granular  contents. 
They  are  probably  multinucleate,  since  the  cells  are  very  narrow  and  long, 
but  nearly  always  show  a  nucleus  in  cross-sections.  The  pericycle  cells  are 
often  much  larger  in  the  region  of  the  protophloem  than  elsewhere  (fig. 
35).  The  protophloems  have  already  passed  their  greatest  density  and 
prominence  and  the  sieve-tubes  now  appear  mature.  Each  protoxylem 
consists  of  one  or  two  extremely  slender  spiral  elements,  with  one  or  two 
slightly  wider  scalariform  tracheids  on  either  side.  The  two  or  four  large 
central  tracheids  of  the  metaxylem  show  as  yet  no  thickening  of  the  walls 
(figs.  34,  35,  36,  43,44). 

TABLE  4. — Statistics  of  transverse  section  of  root. 


No.  of  cells  in— 

Cortex. 

No.  of  cells  in— 

Epiderm. 

Hypoderm. 

No.  of 
layers. 

No.  of  cells 
In  outer 
layer. 

No.  of  eel  Is 
in  inner 
layer. 

Endoderm. 

Pericycle. 

64 

30 

4 

*22 

20 

19 

21 

49 

19 

4 

14 

24 

18 

20 

40 

!? 

4 

... 

... 

... 

40 

20 

4 

H 

23 

16 

*7 

46 

26 

*i8 

13 

10 

13 

t6i 

27 

22 

20 

15 

*9 

tS2 

28 

4  or  5 

... 

21 

15 

20 

tso 

26 

3 

21 

17 

13 

16 

i  with  3 

14  with  4 

10  with  5 

3  with  6 

*  Immature.  flections  of  one  root,  16  ^  apart. 

Following  all  these  parts  upward  in  an  old  root,  we  find  that  the  epider- 
mis and  outer  soft  layer  of  cortex  wither  after  the  root-hairs  die,  and  are 
ultimately  sloughed  off  (fig.  46).  The  bundle  is  now  protected  by  the 
two  or  three  inner  cortical  layers,  whose  walls  have  thickened  so  as  almost 
to  obliterate  the  lumen.  Lignification  in  the  metaxylem  takes  place  slowly. 
In  a  section  showing  a  withering  epidermis,  and  the  inner  cortex  indurated 


14  STRUCTURE    AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

so  that  the  cell-walls  are  about  one-fourth  the  width  of  the  lumens,  there 
are  (fig.  44)  two  large  tracheids  slightly  thickened,  and  two  in  the  center 
wholly  unthickened  and  containing  protoplasm.  Only  with  the  decay  and 
disruption  of  the  outer  layers  of  the  root  do  the  inner  cortex  and  xylem 
become  fully  mature  (fig.  45).  This  occurs  from  3.5  cm.  to  10  cm.  from 
the  root  tip.  One  can  not  as  a  rule,  obtain  a  transverse  section  showing 
all  of  the  tissues  mature  and  intact. 

These  facts  have  an  important  physiological  significance.  We  suppose 
the  water-supply  of  the  plant  to  come  in  through  the  root-hairs.  But 
where  these  are  functional  the  xylem,  always  considered  the  water-con- 
ducting tissue,  is  decidedly  immature.  It  is  evident  that  lignified  walls  are 
not  necessary  for  the  conduction  of  water  in  the  cells.  It  may  be,  however, 
that  the  inner  cortex,  whose  walls  thicken  at  such  an  early  period,  is  for  a 
time  active  in  water  conduction. 

In  25  out  of  95  roots  examined  (/.  <?.,  26.3  per  cent)  from  localities  in 
Long  Island,  Pennsylvania,  and  Maryland,  a  more  or  less  copious  growth 
of  non-septate  fungus  hyphae  was  found  in  the  middle  cortex  (figs.  52, 
53).  One  of  the  most  pronounced  cases  was  attached  to  a  rhizome  of 
unusual  thickness  and  width  and  with  an  unusually  long  and  rapidly  grow- 
ing meristematic  apex.  In  a  root-tip  from  this  plant,  hyphae  were  seen 
3.07  mm.  from  the  initial  cell.  They  were  located  in  the  epidermis  and 
hypodermis,  with  branches  running  inward.  In  an  older  root,  a  hypha 
was  seen  extending  into  the  root  through  a  root-hair  (fig.  53).  Once  in 
the  middle  cortex,  strong  hyphae  run  from  cell  to  cell,  ramifying  in  each 
cell  to  form  a  dense  granular  mass  (fig.  53).  Sometimes  the  fungus  is 
found  only  on  one  side  of  the  root,  or  in  only  a  few  cells.  Occasionally 
it  spreads  all  the  way  round.  From  the  undoubted  vigor  of  the  host  where 
the  fungus  occurs,  the  early  stage  of  the  root  at  which  it  appears,  and  the 
mode  of  copious  branching  of  the  hyphae  in  the  medio-cortex,  we  feel 
justified  in  considering  that  we  have  to  do  with  a  true  mycorhiza.  On 
account  of  its  inconstancy,  it  may  be  called  facultative.  No  other  poly- 
podiaceous  fern  is  known  to  possess  such  a  commensalism,  though  Janse 
(1895)  has  recorded  a  similar  condition  in  the  aerial  roots  of  Cyathea 
(species  not  given). 

Lateral  rootlets  arise  from  rhizogenous  cells  of  the  endodcrmis,  opposite 
the  xylem  rays,  as  is  universal  in  ferns.  The  endodermis  has  been  shown 
(p.  10)  to  originate  in  the  root  apex  with  two  cells  in  each  segment,  i.  <?., 
one  in  each  sextant.  After  the  segment  is  divided  transversely  into  two 
layers,  there  are  two  endodermal  cells  to  a  sextant,  one  lying  nearer  the 
apex  than  the  other.  In  the  two  opposite  sextants  in  which  the  protoxy- 
lems  are  later  to  form,  the  endodermal  cell  lying  nearer  the  root  apex 
remains  undivided  by  any  radial  walls,  while  its  posterior  and  sister  cell, 
like  all  the  other  endodermal  cells  of  the  root,  is  halved  radially.  This 
large  cell,  extending  clear  across  the  sextant,  is  the  primitive  rhizogenous 


SPOROPHYTE.  15 

cell  (figs.  32,  33,  34).  On  one  side  it  lies  in  a  major  sextant,  on  the  other 
side  in  a  minor;  but  both  of  these  sextants  remain  much  narrower  than 
the  other  four  (fig's.  32,  33),  as  if  to  accommodate  this  undivided  cell. 
As  the  root  elongates  in  this  region,  transverse  divisions  take  place  in 
the  rhizogenous  cell.  The  more  distal  member  in  each  case  retains  its 
identity,  while  the  others  sooner  or  later  divide  radially  and  become  like 
ordinary  endodermal  cells  (figs.  38-40).  If  the  radial  walls  are  slow 
to  appear,  we  may  have  a  row  of  three  or  four  equally  broad  cells  (figs. 
38-40),  of  which  only  the  most  distal  is  rhizogenous.  In  Cyatheaceae  all 
of  the  cells  in  the  same  vertical  line  with  the  rhizogenous  cell  are  said  to  be 
of  the  same  width  as  the  latter  (e.  g.,  Cibotium  regale;  cf.  Sadebeck  1898, 
p.  63).  Demist<zdtia,  therefore,  agrees  with  Polypodiaceae  in  this  respect. 

After  elongation  of  the  root  is  complete,  the  definitive  rhizogenous  cell 
swells  out  into  a  lens-shaped  body  (fig.  34).  On  its  proximal  side  it  is 
cut  once  more  by  a  transverse  wall,  but  this  wall  passes  obliquely  inward 
(fig.  37).  Two  obliquely  longitudinal  walls  follow  (figs.  35,  36,  40,  41)  hew- 
ing out  a  tetrahedral  cell  with  one  face  against  the  cortex,  one  side  toward 
the  stem,  and  the  apex  toward  the  subjacent  pericycle.  This  is  the  rootlet 
initial  (figs.  36,  40,  41),  and  the  three  cells  which  bound  its  sides  are  the 
first  segments  of  the  rootlets.  This  initial  and  all  of  its  segments  proceed 
to  develop  as  in  the  case  of  the  parent  root  (figs.  41-43).  The  rootlet 
being  smaller  than  the  root  (fig.  54),  its  segments  undergo  fewer  divisions 
in  the  cortical  region.  The  xylem  of  the  rootlet  stands  transversely  to 
that  of  the  root.  Therefore  the  protoxylems  are  to  the  right  and  left  if  the 
root  is  held  in  a  vertical  position,  and  the  xylem  band  of  the  rootlet  will 
lie  horizontally.  The  xylems  of  the  rootlet  arise  in  the  second  and  third 
(and  overlying)  segments  formed  from  the  rootlet-initial,  and  in  their 
proximal  sextants. 

Meanwhile  divisions  have  also  occurred  (as  shown  by  mitotic  figures) 
in  the  neighboring  endodermal  and  cortical  cells.  In  the  former  no  regu- 
larity was  observed.  The  cortex,  however,  develops  a  mass  of  small  pro- 
toplasmic cells  directly  over  the  rootlet  (figs.  34,  42,  43)  and  undergoes 
no  induration  here.  The  cells  immediately  adjacent  to  the  root-cap  are 
finally  organized  into  a  special  layer  (fig.  43)  which  advances  through  the 
remaining  cortex,  etc.,  apparently  causing  the  disintegration  and  absorp- 
tion of  these  tissues.  In  the  mature  stage  all  of  the  tissues  of  root  and 
rootlet,  excepting  epidermis  and  outer  cortex  (including  hypodermis),  are 
respectively  continuous.  Certain  inner  cortical  cells  of  the  main  root  bend 
out  into  the  branch,  but  endodermis  and  pericycle  (fig.  55)  connect  by  the 
intervention  of  a  number  of  cubical  cells.  The  xylem  tracheids  of  the 
branch  terminate  abruptly  against  the  side  of  those  of  the  main  root  and 
at  right  angles  to  them  (figs.  56,  57).  The  phloems  connect  in  a  manner 
similar  to  the  xylems.  The  mature  rootlet  repeats  the  structure  of  an 
ordinary  root  on  a  smaller  scale  (fig.  54).  In  a  slender  rootlet  there  may 


16  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

be  but  two  layers  of  true  cortex  between  endodermis  and  hypodermis.  In 
this  case  the  outer  layer  has  six  large  cells  in  a  circle,  and  the  inner  layer 
and  hypodermis  have  twelve  cells  each.  The  sextant  walls  of  the  apex 
thus  persist,  and  may  even  at  times  be  traced  through  the  endodermis  and 
pericycle.  Plainly  this  does  not  in  any  sense  indicate  a  common  origin  of 
endodermis  and  pericycle. 

In  relation  to  the  stem,  the  main  root  originates  very  near  the  apex,  in  that 
layer  of  cells  which  will  subsequently  give  rise  to  both  endodermis  and  peri- 
cycle (fig.  70) .  The  rhizogenous  cell  is  large  and  cubical.  By  three  oblique 
walls  a  tetrahedral  initial  is  early  cut  out,  and  from  this  time  onward  it 
behaves  just  as  it  would  in  a  mature  root.  It  has  no  fixed  position  in  rela- 
tion to  the  stem-initial.  Beneath  (centrad)  the  developing  root-tissues  a 
great  proliferation  of  stem-tissue  takes  place.  The  root  is  thus  borne  half- 
way through  the  cortex,  or  farther,  on  a  ''pedicel"  (figs.  59-61)  while  it 
is  of  itself  digesting  away  the  outer  cortex  and  forming  a  many-layered 
cap.  It  finally  emerges  through  a  ragged  opening  in  the  cauline  cortex 
(fig.  102). 

During  the  elongation  of  the  stem  the  vascular  tissues  connecting  root 
and  stem  are  much  deformed,  with  the  following  result:  Tracing  the 
mature  root  inward,  its  stele  passes  obliquely  half-way  through  the  cortex 
of  the  stem  (fig.  102),  then  bends  sharply  backward,  and  fuses  with  the 
stem  stele.  The  cortex,  endodermis,  and  pericycle  of  both  organs  are 
smoothly  continuous.  But  the  root-xylem,  after  passing  a  little  backward, 
turns  at  an  acute  angle  forward  for  a  short  distance.  Some  elements 
become  at  once  cauline,  and  run  on  forward.  Others,  by  another  sharp 
bend,  turn  .backward  in  joining  the  xylem  of  the  stem.  Rarely  a  tracheid 
runs  directly  from  the  root  into  the  stem  without  a  double  bend.  Phloem 
and  conjunctive  parenchyma  follow  parallel  with  the  xylem.  The  depth 
of  these  bends  varies.  In  any  case,  those  tracheids  which  are  continuous 
from  root  to  stem  must  assume  very  peculiar  shapes  (figs.  58,  61,  62). 
The  bending  occurs  at  an  early  stage  of  the  development,  before  the  cells 
become  lignified  (fig.  61).  When  a  root  originates  from  a  leaf -base  it 
passes  out  in  a  similar  manner.  A  double  bend  occurs  in  the  vascular 
elements,  but  the  folds  are  quite  shallow. 

THE   STEM. 

The  rhizome  is  slender  and  cylindrical  and  more  or  less  branched  (fig. 
3).  A  piece  in  my  collection  from  Bucks  County,  Pennsylvania,  grown  in 
loose  loam,  is  35  cm.  long,  with  branches  15  cm.  and  4  cm.  long.  Another 
rhizome  from  Delaware  County,  Pennsylvania,  is  8  cm.  long  to  a  fork;  one 
branch  runs  23.5  cm.  and  forks  into  parts  4.5  cm.  and  3  cm.  long,  respec- 
tively; the  other  branch  runs  19.5  cm.  to  a  fork,  with  the  parts  22  cm.  and 
13  cm.  long.  The  diameter  varies  from  1.5  mm.  to  4  mm.,  with  a  mean 
of  about  3  mm.  When  fresh  the  rhizomes  are  somewhat  flexible,  but  the 


SPOROPHYTE.  17 

cortex  readily  breaks  across  and  pulls  loose  from  the  much  more  tough  and 
elastic  vascular  core.  The  outer  surface  is  of  a  dark  reddish-brown  color, 
shading-  to  nearly  white  at  the  apices.  In  very  rapidly  growing  rhizomes 
the  soft  white  apical  region  may  be  2  cm.  long,  but  usually  it  is  about 
5  mm.  Glabrous  to  the  unaided  eye,  the  mature  parts  of  the  rhizome  may 
be  seen  with  a  hand  lens  to  be  scattered  over  with  the  bases  of  dead  hairs. 
At  the  apex  the  hairs  themselves  are  very  numerous  and  serve  to  clothe 
the  soft  parts  with  an  efficient  protective  covering  (figs.  70,  106).  Scales 
are  entirely  lacking  from  all  parts  of  the  plant. 

The  leaves  are  inserted  without  articulation,  mostly  alternately  to  right 
and  left  of  the  mid-line  on  the  dorsal  surface  of  the  rhizome.  They  stand 
therefore  in  two  dorso-lateral  rows.*  Since  the  distances  between  them 
range  from  1.6  cm.  to  5.7  cm.  (usually  about  3  cm.),  we  may  speak  of 
definite  nodes  and  internodes  (fig.  3)  (cf.  Boodle,  and  Gwynne-Vaughan). 

Branching  occurs  in  two  ways:  direct  forking  of  the  rhizome,  and  occa- 
sional stem-buds  given  off  from  the  lower  parts  of  the  petioles  (figs.  3,4). 
The  latter  will  be  discussed  in  connection  with  the  leaf.  A  fork  gives  all 
the  appearance  of  a  true  dichotomy,  the  two  branches  spread  equally,  like 
the  arms  of  a  Y,  from  the  parent  axis,  and  a  ridge  runs  over  the  crotch 
(fig.  99)  from  dorsal  to  ventral  surface  of  the  stem.  In  young  stages 
(arms  1  to  2  cm.  long)  the  two  branches  are  alike  in  length  and  diameter, 
but  inequalities  of  growth  soon  cause  them  to  differ.  I  did  not  determine 
how  the  two  initial  cells  originate. 

The  interesting  and  beautiful  concentric  structure  of  the  stem  (fig.  67) 
was  evidently  known  to  De  Bary  (1877,  1884),  and  was  thus  described  by 
Eaton  (1879): 

The  section  shows  a  broad  exterior  ring  of  light-brown  parenchyma;  inside  of  this 
is  a  broad  circle  of  minute  white  starch-cells,  then  scalariform  vessels  in  a  narrow  ring, 
bordered  by  other  minute  cells,  which  are  most  probably  bast  cells;  inside  of  this  is  an- 
other broad  circle  of  starch-cells  and  in  the  very  center  is  a  roundish  mass  of  brown 
sclerenchyma.  The  whole  section  has  such  a  regular  concentric  system  that  it  is  not 
only  very  pretty  to  look  at,  but  would  be  very  well  suited  for  anatomical  study  in  the 
classroom  [p.  341]. 

Gwynne-Vaughan  (1903)  also  says: 

A  perfectly  solenostelic  vascular  system  was  found  in  the  stems  of  all  the  species 
included  in  the  following  list :  Davallia  hirsuta,  marginalis^  strigosa,  platyphylla, 
hirta,  spelunccc,  novce-zeylandice,  Lindsay  a  retusa,  Dicksonia  apiifolia,  cicutaria,  scabra, 
punctiloba,  davallioides,  Pteris  scaberula,  incisa,ludens,  Pellcea  atropurpurea,falcata, 
Jamesonia  imbricata.  All  these  ferns  have  a  creeping,  more  or  less  dorsiventral  rhizome, 
with  the  leaves  arranged  in  two  rows  on  the  upper  surface,  and  their  solenosteles  differ 
from  each  other  and  from  that  of  Loxosoma  as  described  in  Part  I  of  this  paper  [1901] 
in  so  slight  a  degree  that  the  same  description  will  serve  for  them  all  [p.  691]. 

*Of  134  leaf-bases  on  stems  which  were  taken  at  random,  96  insertions  were  dorso- 
lateral  (right  or  left),  21  directly  on  one  side  (right  or  left),  16  dorsal,  and  3  ventral. 
Each  ventral  leaf  springs  from  the  angle  of  a  fork  of  the  stem,  and  bends  upward 
through  the  fork. 


18  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

In  the  mature  internode  (figs.  63,  64,  67,  97)  we  find  externally  an 
irregular  black,  sclerosed  epidermis  (see  table  of  measurements  p.  19). 
The  inner  walls  often  bear  rod-like  thickenings  projecting-  into  the  lumen 
of  the  underlying-  cells  (figf.  63).  Next  within  comes  a  broad  zone  of  black- 
walled  sclerotic  cortex,  ten  to  twelve  cells  deep.  These  cells  (fig.  63,  s) 
are  ang-ular  and  do  not  inclose  intercellular  spaces.  Although  mostly 
appearing  empty,  they  may  contain  considerable  amounts  of  starch,  espe- 
cially in  the  inner  members.  They  are  largest  in  the  middle  of  the  zone. 
There  are  pores  of  different  sizes  and  shapes  irregularly  scattered  over  the 
walls.  The  ends  of  the  cells  are  oblique  or  bluntly  tapering  (fig.  64;  see 
table,  p.  19). 

Sharply  demarcated  from  the  sclerotic  cortex  by  a  sudden  change  in  the 
character  of  the  wall  is  a  narrow  layer  of  starchy  cortex  (figs.  63,  64,  st.), 
This  layer  is  from  three  to  eight  cells  thick.  The  cell-walls  are  thin  and 
colorless.  They  inclose  protoplasm  and  nucleus,  and  are  densely  packed 
with  starch.  Intercellular  spaces  are  easily  perceptible  here  between  the 
rounded  cells.  The  end  walls  are  transverse  or  are  slightly  oblique  (see 
table,  p.  19). 

The  cortex  is  bounded  on  its  inner  side  by  a  continuous  sheath  of  endo- 
dermis — a  circle,  in  cross-section,  of  flattened  but  irregular  cells,  very  poor 
in  contents  (figs.  63,  64,  67,  97).  Each  radial  wall  bears  a  thickened  band 
which  stains  with  safranin  (see  table,  p.  19). 

Within  this  layer  intercellular  spaces  can  be  no  longer  found,  but  we 
encounter  a  thick  ring  of  vascular  tissue,  which  again  incloses  a  rod-like 
core  of  starchy  and  sclerotic  cells  (medulla).  In  short,  the  vascular  sys- 
tem constitutes  a  cylindrical  tube.  The  vascular  ring  itself  shows,  passing, 
from  without  inward,  successive  rings  of — 

(1)  Endodermis.  (7)  Inner  conjunctive  parenchyma. 

(2)  Pericycle.  (8)  Inner  phloem. 

(3)  Protophloem.  (9)   Inner  protophloem. 

(4)  Phloem.  (10)   Inner  pericycle. 

(5)  Conjunctive  parenchyma.  (u)   Inner  endodermis. 

(6)  Xylem. 

In  the  words  of  Gwynne-Vaughan  (1903): 

The  xylem  ring  is  surrounded  both  externally  and  internally  by  a  complete  ring  of 
phloem  and  pericycle,  and  the  whole  is  delimited  from  the  ground  tissue  on  both  sides 
by  a  well-marked  endodermis. 

The  outer  pericycle  (fig.  63)  consists  of  two  or  three  layers  of  angular 
cells,  densely  packed  with  starch.  Their  walls  tend  to  lie  in  radial  and 
tangential  planes,  and  the  radial  walls  are  often  in  continuity  with  those 
of  the  endodermis  (see  table,  p.  19). 

Protophloem  is  difficultly  discernible  in  the  old  stem,  though  it  forms  an 
almost  continuous  ring  of  cells.  The  elements  are  greatly  elongated,  very 
slender,  angular,  of  various  shapes  and  sizes,  with  finely  tapering  ends. 


SPOROPHYTE. 


19 


Only  rarely  do  two  elements  lie  adjacent  radially.  The  walls  are  thick, 
but  not  lig-nified,  and  are  beset  with  deep  pits  with  rounded,  flaring-  aper- 
tures. They  are  best  seen  in  the  very  young-  regions  (fig's.  107,  110) 
where  lignification  is  just  beginning-  to  occur  in  the  xylem  (see  table  below). 
The  phloem  forms  a  continuous  ring-,  one  to  three  cells  in  thickness. 
The  cells  are  angular  and  appear  in  cross-section  to  be  empty;  their  ends 
(fig-.  65)  acute,  but  not  finely  tapering-.  These  are  sieve-tubes,  but  the 
sieve-plates  are  only  found  with  some  difficulty .  I  could  not  demonstrate 
callus,  either  with  azoblue  or  coralline  soda. 

TABLE  ^.—Measurements  in  millimeters  of  cells  of  various  tissues  in  the  stem. 


Tissue 

Length. 

Radial  diameter. 

Tangential  diameter. 

Avrir. 

Max. 

Min. 

Aver. 

Max. 

Min. 

Aver. 

Max. 

Min. 

Kpidermis  

O.  I 

.264 

.336 
.142 

.063 
.01447 
.678 

o.  16 

0.064 

0.02 

•037 

.051 
.042 
.00825 
.0157 
.00892 
.0164 

.0127 
.06 

•0155 
.0083 

•  034 

0.03 
.047 

.066 

•°5 
.009 
.0178 

0.014 
.032 

.032 
.032 
.00714 
.014 

0-035 

0.0372 

0.032 

Outer  sclerotic  cor- 
tex       .... 

Inner  sclerotic  cor- 
tex   . 

•44 
.246 
.078 
.16 

.21 

.088 
•057 

.127 

Starchy  cortex  
Outer  endodermis... 
Outer  pericycle  
Outer  protophloem.. 
Outer  phloem 

.0195 
.0239 

.0214 
.032 

.014 
.0178 

2.  I 

i-5 

.025 

.013 

Outer    conjunctive 
parenchy  ma. 

.167 

Xylem 

4-4 

1.6 

.078 

.021 
.014 
•039 

.032 
.0134 
.0071 
.025 

.04 

•057 

.02 

Inner  phloem 

Inner  endodermis... 
Starchy  medulla  

•°99 
.166 

.149 
.264 

.082 
.105 

.01985 

.022 

.0178 

Between  phloem  and  xylem  lie  the  thin- walled,  ang-ular,  starch-laden  cells 
of  conjunctive  parenchyma  (fig's.  63,  64,  81).  They  are  about  twelve 
times  as  long-  as  wide,  and  have  tran verse  or  oblique  end- walls.  Some  of 
these  cells  may  extend  in  between  the  xylem  tracheids,  and  rarely  such  an 
extension  joins  with  the  inner  conjunctive  parenchyma,  completely  inter- 
rupting- the  xylem.  Sometimes  the  conjunctive  parenchyma  is  interrupted 
and  a  sieve-tube  lies  directly  against  a  scalariform  tracheid. 

With  the  above  exception  the  xylem  is  a  continuous  ring-  of  larger  and 
smaller  scalariform  tracheids,  with  thick,  lignified  walls  (fig's.  63,  67,  97). 
The  middle  lamella  is  clearly  discernible.  In  places  this  ring- includes  but 
one  radially  widened  xylem  element;  in  other  places  it  may  be  three  cells 
thick.  There  are  no  spiral  elements  in  the  stem.  The  tracheids  are  of 
the  usual  long,  pointed  type  (figs.  78,  79;  see  table  above). 

The  inner  tissues  so  closely  resemble  the  outer  that  they  may  be  described 
simply  by  comparison  (figs.  63,  64).  Conjunctive  parenchymas  show  no 
difference.  The  inner  phloem  is  mostly  one,  often  two,  cells  thick,  and  the 
sieve-tubes  are  narrower  than  the  outer  ones  (see  table  above).  Proto- 


20  STRUCTURE    AND    LIFE-HISTORY    OF    HAY-SCENTED    FERN. 

phloems  present  no  differences.  The  inner  pericycle  is  one  to  two,  rarely 
three,  cells  thick.  Inner  endodermis  is  like  the  outer  in  cross-sections,  but 
seems  to  have  longer  cells  (see  table,  p.  19). 

The  layer  of  starchy  medulla  inside  the  vascular  ring-  corresponds  with 
that  on  the  outside.  In  a  rhizome  with  six  to  eight  layers  outside,  there  are 
about  seven  inside.  In  another  with  three  or  four  (mostly  three)  layers 
outside,  there  are  two  or  three  (mostly  three)  inside.  But  the  inner  cells 
are  smaller  than  the  outer  (see  table,  p.  19).  The  inner  sclerenchyma 
cells  (sclerotic  medulla)  are  longer  and  narrower  than  the  outer,  and  have 
thicker  and  blacker  walls  (figs.  63,  64,  76,  77,  80).  They  form  a  core 
from  twelve  to  twenty-two  cells  in  diameter. 

The  above  type  of  stem  is  called  by  Gwynne-Vaughan  (1901)  a  solenostele 
(adj.  solenostelic)  and  by  Jeffrey  (1897)  an  amphiphloic  siphonostele.  The 
description  may  serve  as  a  definition  of  these  terms. 

At  the  node  (figs.  3,  4,  66)  the  cylindrical  leaf -base  springs  from  the 
slightly  larger  stem  at  a  right  or  acute  angle,  usually  without  altering  the 
size  or  shape  of  the  stem.  Occasionally  the  stem  is  slightly  enlarged 
below  the  node,  and  rarely  there  is  a  slightly  prominent  ridge  between  leaf 
and  stem,  as  at  a  fork. 

The  leaf -trace  or  vascular  bundle  of  the  leaf  (petiolar  meristele)  leaves 
the  stem  as  a  trough-like  band  (horseshoe-shaped  in  transverse  section) 
which  is  of  the  same  thickness  as  the  wall  of  the  vascular  tube  of  the  stem 
(fig.  82) .  The  concavity  of  the  trough  faces  obliquely  upward  and  forward 
in  most  leaves.  But  where  the  leaf-insertion  is  ventral  (figs.  83-87)  or 
lateral  the  trace  faces  directly  tipward.  When  the  insertion  is  dorsal  the 
trace  faces  directly  forward.  At  the  place  where  the  leaf -trace  leaves  the 
tubular  vascular  system  of  the  stem  a  distinct  leaf- gap  occurs  (fig.  82). 
This  is  a  narrow  slit  in  the  stem  bundle,  through  which  the  medullary  and 
cortical  tissues  become  continuous.  The  gaps  differ  in  shape  and  in  their 
exact  relation  to  the  leaf -trace.  One  gap  is  11  mm.  long  and  1.2  mm. 
wide,  with  acute  ends,  and  with  the  leaf -trace  attached  near  the  middle  of 
the  ventral  side.  Another  is  14  mm.  by  1  mm.  A  third  is  1.8  mm.  by 
0.3  mm.,  rounded  at  both  ends,  with  the  leaf -trace  occupying  nearly  all  of 
one  side.  The  average  size  (of  ten)  is  5.45  mm.  long  and  0.53  mm.  wide. 
Usually  the  anterior  end  is  rounded  and  the  posterior  end  tapering  and 
acute,  with  the  leaf -trace  attached  along  one  side,  at  or  near  the  anterior 
end.  Such  a  gap  is  figured  by  Gwynne-Vaughan  (1903,  plate  33,  fig.  l). 
When  the  leaf-insertion  is  dorsal  the  trace  arises  symmetrically  from  the 
rounded  posterior  end  of  the  gap.  Lateral  leaf -traces  differ  scarcely  at  all 
in  their  origin  from  the  usual  dorso-lateral  type.  Ventral  leaves,  spring- 
ing from  a  fork,  are  symmetrically  attached  to  each  arm  of  the  stem  (figs. 
83-87 ) .  The  trace  lies  like  a  trough  with  its  concavity  upward .  Approach- 
ing such  a  nodal  fork  along  the  main  stem,  the  stele  first  becomes  wide 
and  flat.  Then  a  slit  is  found  on  the  upper  side,  and  as  the  branches 


SPOROPHYTE.  21 

separate  this  slit  forms  a  leaf-gap  in  the  adjacent  (inner)  face  of  each 
branch.  From  the  lower  margin  of  both  gaps  the  trough-like  leaf -trace 
comes  off,  forming  for  a  time  a  connection  across  the  fork  from  one  branch 
to  the  other.  It  soon  becomes  distinct  from  both.  Leaf -gaps  are  easily 
dissected  out,  since  the  tissues  readily  separate  along  the  line  of  the  endo- 
dermis. 

As  stated  above,  the  cortex  and  medulla  of  the  stem  come  into  contact 
or  continuity  through  the  leaf-gap  (fig.  100).  The  starchy  layers  always 
connect,  and  sometimes  a  strand  of  sclerotic  cells  connects  the  outer  cortex 
with  the  similar  central  medulla.  In  about  half  the  nodes  examined  (9  out 
of  20)  the  sclerotic  medulla  passes  the  leaf- gap  as  a  solid  rod  unchanged. 
In  one -fifth  (4)  it  connects  directly  with  the  outer  cortex  through  the 
wide  leaf -gaps.  In  7  a  rod  of  sclerenchyma  passes  from  the  medulla  out- 
ward in  the  groove  of  the  leaf -trace  to  vanish  in  the  petiole  or  to  become 
continuous  there  with  a  peripheral  layer  of  similar  cells.  This  rod  may 
originate  independently  in  the  starchy  medulla  shortly  below  the  node,  or 
it  may  begin  as  a  ridge  on  the  sclerotic  medulla,  which  is  gradually  con- 
stricted off.  These  different  arrangements  of  sclerenchyma  may  occur  at 
successive  nodes  of  one  stem. 

Between  the  cortex  and  the  xylem  of  the  stem,  all  of  the  inner  and  outer 
tissues  become  continuous  around  the  margins  of  the  leaf -gap— endodermis 
with  endodermis,  pericycle  with  pericycle,  phloem  with  phloem,  and  con- 
junctive parenchyma  with  conjunctive  parenchyma  (fig.  108).  Or,  the 
phloem  may  become  very  thin,  or  may  be  completely  interrupted  for  a 
short  distance  on  one  or  other  side  of  the  gap.  A  transverse  section  of 
the  stem  through  a  leaf -gap  shows  the  vascular  system  as  a  deep,  round 
horseshoe  (fig.  100).  No  new  tissue  elements  are  seen  at  the  nodes. 
Spiral  vessels  are  not  found  in  leaf -trace  or  stem.  The  cells  bend  out 
from  stem  to  leaf  by  gentle  curves,  without  any  noticeable  peculiarities. 

Where  the  stem  forks  each  tissue  system  remains  continuous  and 
unbroken  (fig.  99).  There  is  no  ramular  gap.  One  can  best  imagine  the 
structure  by  starting  with  a  Y-shaped  object  made  of  round  rods,  welded 
together  below.  Let  this  represent  the  sclerotic  medulla.  We  dip  the 
object  into  melted  wax,  coating  it  all  over;  this  represents  the  layer  of 
starchy  medulla.  Successive  coatings  of  suitable  thickness  may  represent 
inner  endodermis,  inner  pericycle,  inner  phloem,  xylem,  outer  phloem,  outer 
pericycle,  outer  endodermis,  starchy  cortex,  sclerotic  cortex,  and  epidermis. 
In  the  angle  of  the  Y  the  continuity  of  tissues  from  one  arm  to  the  other 
is  strikingly  smooth  and  regular.  A  single  scalariform  tracheid  may 
extend  for  a  long  distance  in  each  arm.  On  the  sides  of  the  fork  this  con- 
tinuity involves  angular  elements  of  peculiar  shapes  (fig.  98). 

The  apex  of  the  stem  is  so  clothed  with  hairs  as  to  appear  smoothly 
rounded  (fig.  3).  Under  this  covering  there  is  a  shallow,  basin-like  de- 
pression (fig.  70),  not  often  symmetrical,  at  the  tip  of  the  stem.  A  low 


22  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

protuberance  standing*  out  in  the  center  of  this  basin  is  the  growing  point. 
Its  surface  is  naked  and  is  rendered  irregular  by  leaf -rudiments.  At  the 
top  of  the  protuberance  is  the  stem-initial — a  narrow,  irregularly  triangular 
cell.  In  longitudinal  section  it  is  deeper  (0.0642  mm.  to  0.07  mm.)  than 
any  other  cell,  excepting  a  newly  formed  segment  (figs.  106,  129).  But 
in  cross-section  it  is  smaller  than  many  of  its  near  neighbors  (figs.  71,  103, 
109).  This  narrowness  makes  it  difficult  to  recognize.  Further,  as  the 
protuberance  in  which  it  stands  varies  in  apparent  position  according  to 
the  development  of  the  young  leaves,  one  can  not  be  sure  of  getting  satis- 
factory sections  of  it  by  cutting  a  bit  of  stem  in  an  exactly  transverse  or 
longitudinal  plane. 

Segments  are  cut  off  in  regular  succession  on  the  three  interior  faces  of 
the  initial.  As  I  could  not,  even  with  much  effort,  distinguish  any  regular 
position  of  the  initial  with  regard  to  dorsal  and  ventral  surfaces  of  the 
stem,  we  can  not  speak  of  dorsal  or  ventral  segments.  The  irregular 
arrangement  of  the  leaves  is  probably  related  to  this  irregularity  of  the 
position  of  the  stem-initial.  The  order  in  which  the  segments  are  cut  off 
is  either  from  left  to  right  or  right  to  left,  the  two  occurring  in  about  equal 
numbers  in  my  preparations  (7  counter-clockwise,  5  clockwise,  from  older 
to  younger). 

Each  segment  is  divided  first  by  a  periclinal  wall  near  its  inner  end. 
The  small,  deep-lying  cell  thus  formed  gives  rise  to  the  medulla  (fig.  106). 
The  outer  cell  is  next  cut  by  the  sextant  wall — a  radial  anticline,  dividing 
the  cell  nearly  into  halves  ("sextants").  This  wall  remains  prominent 
for  a  comparatively  long  time  (figs.  71-75,  103,  109)  (</.  Bower's  figures, 
1889).  The  relative  sequence  of  the  following  anticlines  and  periclines 
was  not  determined.  The  second  periclinal  wall  is  formed  near  the  inner 
end  of  the  columnar  partial  segment  or  sextant,  giving  an  inner  nearly 
cubical  cell  and  an  outer  columnar  one  (fig.  106).  The  inner  of  these 
(plerome  rudiment)  gives  rise  to  the  vascular  system  of  the  stem,  including 
outer  and  inner  endodermis.  The  sextants  are  usually  halved  longitudi- 
nally at  right  angles  to  the  sextant  wall  (fig.  73),  and  as  many  as  sixteen 
to  twenty  rectangular  cells  may  be  formed  by  walls  at  right  angles  to  the 
two  just  mentioned  (figs.  75,  103).  Very  often  oblique  walls  break  up  the 
symmetry.  The  outer  cells  are  repeatedly  divided  by  periclines  near  the 
inner  end  (fig.  106)  until,  after  four  or  five  such  partitions,  the  remaining 
outer  portion  is  reduced  to  the  depth  of  the  epidermis .  Division  then  ceases . 
Meanwhile  the  whole  segment  has  been  pushed  farther  and  farther  from  the 
growing  point  of  the  stem.  The  last  pericline  occurs  in  cells  which  are 
nearly  half-way  up  on  the  sides  of  the  basin-like  depression  of  the  stem  apex. 

Near  the  lowest  part  of  this  depression  arise  the  hairs  which  clothe  the 
apex  (fig.  106).  A  superficial  cell  bulges  out  slightly  and  is  cut  obliquely. 
The  outer  member  enlarges  in  length  and  diameter,  and  is  divided  by 
several  septa.  These  divisions  are  often  intercalary.  The  two  basal  cells 


SPOROPHYTE.  23 

also  straighten  up  their  originally  oblique  wall,  until  it  stands  perpendic- 
ular to  the  surface  of  the  stem.  Thus  there  results  a  basal  cell  of  a  hair, 
with  a  hairless  sister-cell  beside  it.  A  similar  development  of  protective 
ramentum  was  described  by  the  writer  on  the  stem-tip  of  Nymphaea. 

Returning  to  the  plerome  rudiment,  it  develops  much  more  slowly  than 
the  cortex.  It  divides  periclinally  into  two  equal  parts  (fig.  106)  and  each 
of  these  again  by  similar  walls,  giving  four  layers  of  cells  in  the  plerome. 
Apparently  the  outermost  and  innermost  of  these  give  rise  to  pericycle  and 
endodermis,  while  the  two  median  probably  produce  xylem  and  phloem. 
Certain  it  is  that  all  the  tissues  just  named  come  from  the  four  cells  in 
question.  It  is  also  certain  that  the  endodermis  is  formed  at  the  last  peri- 
clinical  division  in  the  outermost  layer  of  plerome,  and  each  endodermal 
element  is  a  sister  cell  to  the  pericyclic  cell  radially  next  to  it.  This  has 
been  suspected  by  several  writers  for  several  ferns,  by  reason  of  the  con- 
tinuity of  the  radial  walls.  I  was  able  to  prove  it  for  Dennst&dtia  by  find- 
ing a  number  of  mitoses  (</.  fig.  70,  <5). 

The  stem  very  quickly  attains  its  final  diameter;  hence  its  broadly 
rounded  end.  At  a  distance  of  0.24  mm.  from  the  initial  cell,  in  an  aver- 
age instance,  all  the  cells  have  reached  their  ultimate  width.  Already  at 
0.18  mm.  in  this  case  the  epidermal  cell- walls  are  thickening  and  becoming 
dark  brown.  At  0.345  mm.  the  protophloem  is  mature  and  at  0.5  mm. 
lignification  is  beginning  in  the  xylem.  In  another  case,  however,  the 
first  thickenings  of  xylem  occurred  at  6  mm.  from  the  apex,  and  in  another 
at  0.18  mm.  (cf.  fig.  70). 

Excepting  the  epidermis,  the  first  tissue  to  mature  is  the  protophloem 
(fig.  107).  For  some  time  it  forms  a  prominent  ring  of  small,  angular, 
thick- walled  fibers  near  each  boundary  of  the  vascular  bundle.  The  walls 
stain  deeply  with  haematoxylin.  Seen  on  the  side,  the  cells  are  very  long 
and  slender,  and  the  walls  are  peculiarly  and  irregularly  pitted.  The  xylem 
matures  very  irregularly.  A  cell  here  and  another  there  become  lignified, 
apparently  without  any  order  (fig.  110).  The  larger  tracheids  precede 
the  smaller,  the  first  ones  being  often  near  the  exit  of  a  root  or  leaf.  No 
spiral  cells  are  formed,  and  there  is  nothing  that  could  be  called  protoxylem. 

THE    LEAF. 

In  the  taxonomic  literature  of  ferns  the  chief  attention  is  directed  to  the 
leaf  and  its  important  appendages.  Thus  several  references  have  already 
been  made  to  the  leaf  of  Dennst&dtia  (figs.  1,2).  In  the  following  descrip- 
tion we  shall  designate  as  petiole,  the  leaf -stalk,  from  the  rhizome  to  the 
lowest  pinna.  All  above  this  is  blade.  The  continuation  of  the  petiole  in 
the  blade  we  shall  call  rachis,  and  the  thin  expansion  of  the  leaf  lamina. 

All  of  the  leaves  are  alike  in  general  appearance  and  in  structure.  There 
is  no  morphological  distinction  of  sporophyll  and  trophophyll,  although  for 
various  undetermined  reasons  some  leaves  are  fertile  and  others  sterile. 
Both  kinds  are  produced  throughout  the  season,  though  the  greatest  devel- 


24 


STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 


opment  occurs  in  May  and  June.  Two  to  five  leaves  is  the  common  annual 
growth  from  each  branch  of  the  stem.  With  considerable  accuracy  each 
leaf  faces  the  chief  source  of  light.  When  growing1  around  an  old  stump 
or  a  bowlder,  the  leaves  on  every  side  turn  their  backs  to  it.  On  steep 
hillsides,  also,  the  leaves  face  downhill.  While  not  every  leaf,  by  any 
means,  stands  thus,  the  general  effect  is  very  noticeable.  The  leaves  stand 
nearly  erect,  but  the  blade  is  gently  curved  backward.  A  leaf  which  ma- 
tures in  June  (first  crop)  turns  yellow  in  August  or  September  in  eastern 
Pennsylvania  and  Maryland,  by  reason  of  old  age  (whatever  that  may  be). 
In  New  England  the  first  leaves  persist  throughout  the  season.  The  first 
sharp  frost  kills  all  of  the  foliage  of  Dennstcedtia. 

TABLE  6.— Data  of  the  leaf. 


No. 

Total 
length. 

Length  of— 

Maxi- 
mum 
width  of 
leaf. 

Distance  oi 
widest  part 
from  base 
of  lamina. 

Diameter 
of  petiole. 

No.  of 
pairs  of 
pinnae. 

Maxi- 
mum No. 
of  pairs  of 
pinnules. 

Petiole. 

Blade. 

cm. 

cm. 

cm. 

cm. 

cm. 

mm. 

I 

Ill 

23 

88 

21 

24 

2-5 

46 

24 

2 

53 

13 

40 

16.3 

15 

2.2 

37 

22 

«„„,    3 

33-5 

7 

26.5 

6.8 

12 

1.8 

3° 

J3 

4 

41 

10 

31 

11.7 

12.5 

1.8 

32 

«9 

Av.of  10 

60.38 

14.2 

46.18 

16.49 

15-7 

2.02 

37-5 

21.5 

The  petiole  is  slender,  smooth,  " chestnut-brown"  (Clute,  1901),  chan- 
neled on  the  upper  (ventral)  surface,  about  one-fourth  of  the  total  length 
of  the  leaf  (not  one-half,  Clute,  1901).  It  is  slightly  stouter  at  base,  e.  g., 
3  mm.  in  diameter  below  and  2.5  mm.  above.  The  lower  part  is  nearly 
always  curved,  often  very  much  so,  because  of  the  obstructions  the  leaf 
meets  in  coming  out  of  the  soil.  Above  the  earth  it  is  straight  and  nearly 
erect. 

The  brown  color  of  the  petiole  is  due  to  pigment  (phlobaphene  ?)  in  the 
cell- walls  of  the  epidermis  and  outer  cortex.  At  the  base,  the  cortex  may 
be  colored  to  a  depth  of  nine  cells.  Passing  upward  along  a  newly  ma- 
tured leaf,  the  layer  grows  thinner,  and  just  below  the  first  pinnae  there  is 
often  no  pigment  at  all.  But  the  coloring  advances  upward  with  the  age 
of  the  frond,  until  all  of  the  rachis  may  become  brown.  The  epidermal 
cells  are  very  irregular  in  size.  Near  the  rhizome  they  are  polyg'onal  and 
are  about  twice  as  long  as  broad.  They  become  longer  above.  At  1  cm. 
from  the  rhizome  they  are  five  times,  and  just  below  the  blade  seven  to 
eleven  times,  longer  than  wide.  In  transverse  section  (fig.  69)  they  are. 
nearly  isodiametric,  but  of  very  different  depths.  Each  cell  bulges  out  a 
little  on  the  surface  of  the  petiole.  The  cell-walls  are  thickly  lignified, 
and  bear  numerous  pits  suggesting  a  continuity  of  protoplasm  from  cell  to 
cell.  There  are  many  hairs,  both  glandular  (fig.  249)  and  acicular  (fig. 
258,  b)  on  the  young  petiole,  but  they  wither  or  are  completely  shed  at 


SPOROPHYTE.  25 

maturity,  leaving-  only  the  oval  basal  cell  to  show  where  they  stood.  The 
hairs  are  of  the  same  character  as  those  on  the  lamina.  They  will  be 
described  later. 

Beneath  the  epidermis  is  a  layer  of  brown,  thick- walled  sclerenchyma, 
as  already  mentioned  (cf.  fig.  69).  In  the  petiole  proper  these  cells  are 
long*,  and  tapering  at  each  end.  Near  the  node  they  become  shorter  until 
they  reach  the  dimensions  of  the  cells  of  the  sclerotic  cortex  of  the  stem, 
with  which  they  are  continuous.  They  may  also  unite  here  with  a  rod  of 
similar  tissue  derived  from  the  medulla  of  the  stem  and  lying  in  the  trough 
of  the  leaf -trace  (cf.  p.  21).  About  the  middle  of  each  side  of  the  petiole 
the  sclerenchyma  is  interrupted  by  an  extension  of  ordinary  parenchyma 
out  to  the  epidermis  (figs.  69,  101).  Stomata  occur  along  this  line  to 
admit  interchange  of  gases  between  the  intercellular  spaces  of  the  paren- 
chyma and  the  outside  air.  For  a  short  distance  near  the  surface  of  the 
ground  the  sclerenchyma  is  not  so  interrupted  and  stomata  do  not  occur; 
but  at  about  1  cm.  from  the  rhizome  the  stomata  and  parenchyma  begin 
again.  The  area  occupied  by  them  here  is  easily  seen,  because  the  walls 
of  the  sclerenchyma  cells  are  of  a  deep-brown  color,  while  those  of  the  par- 
enchyma are  colorless.  This  area  may  end  0.5  to  2  mm.  above  the  rhizome, 
or  may  continue  as  a  visible  ridge  on  the  posterior  side  of  the  leaf -base 
for  1  mm.  or  more  along  the  surface  of  the  node.  The  guard-cells  of 
these  stomata  stand  above  the  level  of  the  surrounding  epidermis.  Such 
lines  of  parenchyma  are  common  in  fern  petioles,  but  by  no  means  universal 
(Thomae,  1886). 

From  the  epidermis  inward,  the  cells  become  larger  in  diameter,  shorter, 
less  acute  at  the  ends,  and  thinner  walled.  Two  to  ten  cells  in,  according 
to  height  and  age  of  section,  we  find  soft  parenchyma,  with  large  watery 
cells  bearing  chlorophyll.  These  become  smaller  again  next  to  the  vas- 
cular bundle.  They  are  in  contact  with  the  endodermis  all  around  the 
bundle.  This  layer  has  many  intercellular  spaces  in  its  middle  portion. 

The  bundle  itself  is  shaped  like  a  trough,  opening  toward  the  upper 
surf  ace  of  the  leaf.  In  transverse  section  near  the  rhizome  (figs.  82,  100, 101) 
it  is  U-shaped,  or  very  nearly  like  the  periphery  of  a  semicircle.  Its  thick- 
ness is  about  the  same  all  round.  Higher  up  the  petiole  it  is  more  V-shaped, 
flattened  at  the  angle  (fig.  68),  and  swollen  at  the  tips  of  the  short  arms. 
The  endodermis  bears  the  typical  Caspary's  band.  The  contents  of  its 
cells  take  up  stains  with  avidity,  and  probably  include  mucilage.  A  par- 
enchymatous  layer  within  the  endodermis  may  be  termed  pericycle.  Of 
two  cells  thickness  in  most  places,  it  thins  off  to  one  cell  around  the  tips  of 
the  arms  of  the  bundle,  and  becomes  three-celled  on  the  outer  side  of  each 
arm  (fig.  68).  At  the  latter  place,  also,  the  middle  cells  enlarge  greatly  to 
form  a  very  peculiar  open  tissue.  The  thin  band  of  xylem  in  the  midst  of 
the  bundle  follows  the  latter  in  general  shape,  but  is  more  curved  in  its 
outlines.  At  the  ends  of  the  U  or  V  it  approaches  very  near  to  the  peri- 


26  STRUCTURE   AND    LIFE-HISTORY    OF    HAY-SCENTED    FERN. 

cycle  and  the  tips  are  bent  sharply  inward  or  "hooked"  (figs.  68,  69,  88-92). 
The  "hook"  is  short  at  the  base  of  the  petiole,  and  much  deeper  above. 
Around  the  xylem  there  is  a  layer  of  conjunctive  parenchyma.  Between 
this  and  the  pericycle  lies  the  phloem.  Its  outermost  layer  all  round  is 
early  developed  as  protophloem  like  that  of  the  stem.  It  appears  after  the 
protoxylems,  and  develops  first  on  the  outer  side  of  each  arm  of  the  bundle. 
Soon  afterward  it  appears  on  the  inner  side  of  each  arm.  These  four  patches 
spread  by  addition  of  elements  at  each  end  until  they  meet  and  form  a 
continuous  sheath.  The  bulk  of  the  phloem  consists  of  sieve-tubes.  No 
protoxylem  elements  (spiral  cells)  are  found  at  the  base  of  the  petiole,  but 
they  appear  shortly  above,  and  are  on  the  inner  (upper,  ventral)  side  of 
the  xylem.  The  first  to  appear  are  two  patches  of  slender  spiral,  annular, 
and  spiro-annular  elements,  one  in  each  corner  of  the  flattened  angle  of  the 
V-shaped  xylem.  Later  another  group  (and  finally  two)  appears  on  each 
arm  beneath  the  hooked  end  of  the  xylem.  Thus  there  are  six  protoxylems 
in  all  (fig.  68).  They  develop  when  the  petiole  is  very  young.  But  a 
very  great  enlargement  of  the  tissues,  both  in  length  and  breadth,  takes 
place  later,  by  which  the  protoxylem  elements  are  quite  torn  to  pieces. 
Neighboring  parenchyma  cells  then  push  in  to  occupy  the  space,  and  the 
remaining  lignin  rings  and  spirals  are  often  pushed  out  of  their  original 
places  (figs.  116,  117).  Thus  originates  the  "cavity-parenchyma"  of 
Russow  (1871)  (cf.  Gwynne-Vaughan,  1901,  p.  87).  Its  cells  retain  a 
fairly  regular  rectangular  shape  and  are  thin -walled. 

The  blade  is  from  30  to  90  cm.  long  (see  table  6)  and  7  to  20  cm.  wide, 
lanceolate  in  outline,  with  the  widest  part  from  5  to  40cm.  above  the  base. 
It  is  pubescent,  very  soft  in  texture,  and  quickly  wilts  when  plucked  or 
frosted.  Its  delicate  yellowish-green  color  has  been  mentioned  above.  It 
is  thrice  pinnate  (fig.  2)  with  the  margins  of  the  ultimate  segments  deeply 
crenate  (fig.  5).  The  veins  are  forked,  without  anastomoses.  The  verna- 
tion is  of  the  typical  circinate  kind  out  to  the  divisions  of  the  third  degree. 
The  crenations  develop  as  the  leaf  unfolds. 

The  number  of  pinnae  varies  from  30  to  50  pairs,  and  the  maximum 
number  of  pinnules  on  a  single  pinna  is  13  to  25  (see  table  6).  Though 
we  speak  of  pairs  of  pinnae,  they  are  not  exactly  opposite.  One  of  the 
lowest  pair  may  be  from  1  to  7  mm.  below  the  other.  Those  of  the  next 
pair,  2.5  to  8  cm.  above,  are  similarly  separated  from  one  another.  Farther 
up,  the  pairs  of  pinnae  and  the  individuals  of  each  pair  are  closer  together, 
but  the  separation  of  the  members  of  each  pair  is  sufficient  to  make  them 
appear  almost  alternate.  Near  the  apex  of  the  leaf  the  rachis  is  much  like 
a  midrib,  and  the  divisions  of  the  leaf  diminish  in  size  and  degree.  The 
uppermost  "pinnae"  are  mere  crenations  of  the  margin  of  a  winged  rachis. 
But  morphologically  they  are  pinnae.  The  larger  pinnae,  in  a  similar 
manner,  have  large,  twice-divided  pinnules;  but  these  become  smaller  the 
farther  they  are  from  the  rachis,  until  they,  too,  become  mere  crenations. 


SPOROPHYTE.  27 

The  rachis  of  the  leaf  repeats  in  general  the  structure  of  the  petiole. 
It  is  deeply  channeled  above,  rounded  beneath  (fig:.  69).  The  epidermis 
is  very  thick-walled,  and  is  supported  by  a  layer  of  sclerenchyma.  This 
layer  is  thinner  than  it  is  in  the  petiole,  especially  on  the  back  and  sides  of 
the  rachis.  In  the  ridge  on  either  side  of  the  groove  it  remains  strong. 
About  midway  of  each  side  of  the  rachis  there  is  a  line  of  spongy  paren- 
chyma with  chloroplasts.  Here  the  sclerotic  sheath  is  interrupted  and 
stomata  are  found  in  the  epidermis  (figs.  69,  114).  The  vascular  bundle 
becomes  narrower  as  we  go  up  the  leaf.  From  a  very  short,  thick,  V-shaped 
cross  section  it  finally  becomes  oval.  Now,  the  xylem  is  a  band  with 
hooked  ends.  The  protoxylems  are  only  two,  lying  inside  the  hooks. 
Cavity  parenchyma  still  accompanies  them  (fig.  114). 

The  oval  form  of  bundle  just  described  is  also  found  in  the  base  of  the 
rib  of  the  larger  pinnae.  These  ribs,  indeed,  fully  repeat  the  outlines  and 
structure  of  the  upper  part  of  the  rachis.  The  vascular  bundle  of  the  rib 
springs  from  that  of  the  rachis  in  the  following  manner  (</.  figs.  88-92). 
The  hook  of  the  xylem  at  one  end  of  the  U-shaped  petiolar  bundle  grad- 
ually becomes  twice  as  deep  as  before,  and  a  bridge  of  xylem  is  formed 
across  the  middle  of  the  hook.  A  constriction  now  cuts  through  the  bridge, 
separating  from  the  bend  of  the  hook  a  small  ring  of  xylem  filled  with 
phloem.  The  constriction  later  affects  the  endodermis,  and  the  new  bundle 
is  completely  separated.  As  it  bends  out  into  the  pinna,  the  xylem  ring 
grows  thicker  below  and  thins  out  to  nothing  above,  until  only  a  single 
transverse  band  of  tracheids  remains  in  the  middle  of  the  bundle.  A  strand 
of  protoxylem  lies  on  the  upper  side  of  this  band,  and  is  continuous  with 
that  of  the  rachis. 

The  veins  and  veinlets  of  the  leaf  are  collateral  in  structure,  cylindrical, 
with  distinct  endodermis.  Their  xylem  consists  wholly  of  spiral  tracheids. 
The  ribs  of  the  uppermost  pinnae  are  also  collateral  throughout,  with  xylem 
above  and  phloem  beneath. 

The  structure  of  the  lamina  is  very  simple.  An  unbroken  epidermis  of 
wavy-margined  cells  (fig.  112)  covers  the  upper  surface.  If  any  cuticle 
is  present,  it  is  extremely  thin.  Over  the  veins  the  cells  are  elongated  and 
approximately  rectangular.  The  lower  epidermis  (fig.  Ill)  bears  many 
large  oval  stomata  about  0.023  mm.  by  0.038  mm.  There  are  about  eight 
of  them  per  square  millimeter.  They  are  set  exactly  level  with  the 
epidermal  cells.  Copeland  speaks  of  them  as  follows  (1902,  pp.  349,  350): 

In  the  Polypodiaceae  I  have  examined,  there  is  an  approach  to  what  Haberlandt 
calls  the  type  [of  stoma]  of  swimming  plants,  in  that  the  ridge  of  entrance  is  well 
developed,  while  the  ridge  of  exit  is  inconspicuous  or  not  present.  In  Dennstcudtia 
punctilobula  Bernh.  (figs.  40,  41)  \cf.  our  fig.  104]  this  thickening  of  the  ridge  of  entrance 
has  gone  far  enough  to  give  the  stoma  a  rigid  appearance,  but  it  is  really  motile. 
Opening  seems  to  be  effected  by  a  movement  of  the  ridge  of  entrance  outward  as  well 
as  backward,  such  as  must  occur  in  lesser  degree  in  the  case  of  Angiopteris.  The  guard- 
cells  of  Dennstcedtia  are  thin-walled  and  shallow  at  the  ends. 


28 


STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 


la  the  following  table  the  depth  is  measured  from  the  ridge  of  entrance  down  to 
the  deepest  dorsal  focus.     The  stoma  was  closed  by  displacing  water  with  alcohol. 


Open. 

Closed. 

Width  of  stoma  

M 
-?O 

/* 
28   c 

Width  of  guard-cells  

13    ^  to  1  4 

Mto  14  c 

Width  of  pore..       

2     ^ 

o 

Length  of  stoma  

44 

4C 

Depth  of  stoma  

17 

14 

[P-  35°]  The  first  effect  of  the  alcohol  is  to  widen  the  pore,  which  then  gradually 
closes,  the  sides  becoming  apparently  straight  before  they  meet.  The  increase  in  depth 
at  the  ends,  which  is  partly  responsible  for  opening  the  pore  of  this  stoma,  works  to 
better  advantage  than  in  the  stoma  of  Osmunda. 

The  cells  of  the  lower  epidermis  (.fig.  111)  are  smaller  and  more  wavy 
than  those  of  the  tipper  surface.  All  of  the  epidermal  cells  contain  chloro- 
plasts,  but  they  are  especially  abundant  in  the  guard-cells.  The  thickness 
of  the  lamina  runs  from  0.06  mm.  at  the  veinlets  to  0.09  mm.  where  the 
mesophyll  is  well  developed.  The  air-spaces  are  especially  large  in  the 
lower  half  of  the  spongy  parenchyma.  A  continuous  layer  of  irregular 
cells  lines  the  upper  epidermis,  but  there  is  nothing  that  could  be  called 
palisade  tissue  (fig.  113). 

Scattered  plentifully  all  over  the  leaf  are  hairs  of  two  kinds — acicular 
(fig.  258,  b}  and  glandular  (figs.  105,  113,  249).  The  first  are  simple,  acute, 
septate,  often  1  to  2  mm.  long.  The  latter  are  simple,  septate,  with  a 
spherical  terminal  cell,  and  from  0.08  mm.  to  1  mm.  long.  The  terminal  cell 
(or  sometimes  two  cells)  is  surrounded  by  a  globule  of  secretion.  In  this 
doubtless  resides  the  ethereal  oil  which  gives  the  characteristic  scent  to 
the  plant.  Waters  (1903,  p.  290)  states  that  the  odor  is  stronger  in  plants 
grown  in  dry,  sunny  places  than  in  those  grown  in  shade,  and  that  it  is 
changed  and  intensified  in  drying  the  leaves.  By  "distilling  with  steam" 
a  "considerable  quantity  of  the  partly  dried  ferns,  .  .  .  two  or  three 
drops  of  oil  were  obtained  ...  It  had  a  rather  disagreeable  odor,  but 
when  a  drop  or  two  of  a  solution  of  the  oil  in  a  large  amount  of  ether  was 
put  on  paper  and  the  ether  allowed  to  evaporate,  a  very  pleasant  reminder 
of  'new-mown  hay'  resulted"  (Waters,  1903).  One  bottle  of  fronds  pre- 
served in  50  per  cent  alcohol  has  retained  the  odor  strongly,  and  it  adheres 
very  persistently  to  hands  or  clothing  after  the  alcohol  has  evaporated. 

The  leaf -shoot,  several  times  referred  to  above,  attracted  my  attention 
in  the  fall  of  1901 .  It  is  the  stem  which  comes  off  from  the  base  of  the  petiole 
(fig.  4).  About  20  per  cent  of  the  leaves  bear  siich  shoots,  the  remaining 
80  per  cent  showing  no  trace  of  them  whatever.  The  shoot  arises  on  the 
side  of  the  petiole  at  a  very  early  stage  of  development,  but  I  was  not  able 
to  find  its  relation  to  the  sectioning  of  the  segments  of  the  leaf.  I  believe 


SPOROPHYTE.  29 

the  shoots  arise  often  after  the  section  lines  are  obliterated.  They  lie 
above  (ventral  to)  the  stomatic  line  of  the  petiole.  At  maturity  the  shoot 
is  from  3  to  8  mm.  (average  of  10  =  5.4  mm.)  from  the  rhizome.  It  is  in 
all  respects  a  stem.  Its  tubular  stele  is  attached  nearly  at  right  angles  to 
one  margin  of  the  trough-like  vascular  bundle  of  the  petiole  (fig.  82). 
The  stele  usually  appears  truncate  at  its  point  of  origin,  but  it  may  be  slit 
on  its  upper  side,  giving  a  trough-like  shape  (figs.  93-96).  I  have  never 
found  any  commissural  strand  connecting  the  shoot  directly  with  the  stem, 
as  noted  by  Gwynne-Vaughan  (1903)  in  other  solenostelic  ferns.  The 
inner  parenchyma  of  the  petiole  is  continuous  with  the  medulla  of  the  shoot. 
Occasionally  two  shoots  arise  on  opposite  sides  of  a  single  petiole;  they  are 
then  either  opposite  or  as  much  as  2  mm.  apart.  The  shoot  may  remain 
dormant  as  a  mere  papilla  for  two  or  three  years,  or  its  growth  may  be 
extremely  slow,  or  it  may  from  the  first  nearly  equal  in  size  the  leaf  from 
which  it  springs,  or  the  leaf  may  fail  to  develop  (owing  to  injury  by  fungi, 
etc.)  and  the  shoots  alone  continue.  Ultimately  the  leaf -shoots  produce 
normal  rhizomes,  as  shown  by  one  which  I  measured  in  March,  1905.  It 
was  12  cm.  long,  1.5  mm.  in  diameter  at  its  origin  and  2.6  mm.  at  4  cm. 
from  its  origin.  During  previous  seasons  it  had  borne  three  leaves,  and 
two  more  were  ready  to  develop  in  1905.  The  apex  had  just  forked. 

The  descriptions  of  leaf -development  given  by  Sadebeck  (1873,  1874, 
1878,  1898),  Kny  (1875),  and  Campbell  (1887,  1895,  1905)  contain  some 
points  which  I  can  not  interpret,  and  the  leaf  of  Dennsttedtia  differs  in  its 
development  from  that  of  the  Hymenophyllacese  as  given  clearly  by  Prantl 
(1875,  a,  <£).  The  leaf  takes  its  origin  from  a  deep  four-sided  prismatic 
cell  in  the  apex  of  the  stem  (figs.  103,  109,  118,  121,  128).  The  cell  is 
sometimes  recognizable  by  its  large  size  in  the  fourth  segment  from  the 
stem  initial  (fig.  109).  It  seems  reasonably  certain  that  not  every  stem 
segment  gives  rise  to  a  leaf,  nor  even  two  out  of  every  three  segments. 
The  location  of  the  leaf -initial  in  the  segment  also  varies  much,  according 
to  the  size  and  rapidity  of  growth  of  the  stem.  It  is  usually  near  one  mar- 
gin of  the  segment  (figs.  103,  109),  and  may  lie  very  near  the  stem-initial 
until  many  divisions  have  occurred  in  it  (figs.  128,  129).  The  leaf-initial 
in  its  earliest  stage  extends  into  the  stem  as  far  as  the  future  boundary  of 
medulla  and  plerome.  Its  divisions  are  different  from  those  of  the  neigh- 
boring cells — a  fact  which  is  related  to  the  formation  of  the  leaf -gap.  No 
definite  order  could  be  discovered  in  the  early  divisions  of  the  leaf -initial. 
It  maintains  its  four-sided  shape  for  some  time  (figs.  118,  121),  then  is  cut 
obliquely  (figs.  121,  122-127)  and  becomes  tetrahedral.  After  forming  a 
few  segments  on  three  sides,  the  initial  ceases  to  form  segments  on  one  of  the 
three  sides  and  it  becomes  '  'two-sided. ' '  Meanwhile,  all  of  the  cells  derived 
from  the  primitive  leaf-initial  are  elongating  and  forming  a  papilla  on  the 
stem  apex,  at  the  tip  of  which  the  definite  apical  cell  of  the  leaf  is  situated 
(fig.  70).  This  cell  is  wedge-shaped  (figs.  123,  130)  and  very  broad  across 


30  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

its  exposed  face.  As  segments  are  cut  off  from  it  alternately  on  the  two 
sides,  it  itself  becomes  narrower,  and  finally  very  slender  (figs.  131,  135). 
Each  segment  divides  first  on  the  ventral  side  by  a  radial  anticline  which 
cuts  off  a  narrow  cell  running  from  the  periphery  to  the  center  of  the 
leaf -rudiment  (figs.  132-134,  140).  A  similar  wall  near  the  dorsal  margin 
of  the  segment  meets  the  first  nearly  at  right  angles,  close  to  the  center 
of  the  leaf -rudiment.  The  two  narrow  cells  may  be  called  sections  (Johnson, 
1898)  and  the  walls  section-walls.  The  remaining  triangular  portion  of 
the  segment  is  a  primary  marginal  cell.  The  segment  enlarges  and  a  wall 
parallel  to  the  segment  walls  (transverse  anticline)  divides  the  primary 
marginal  cell  into  two  equal  secondary  marginal  cells  (figs.  132-134).  In 
each  of  these  two  new  section-walls  occur,  one  ventral,  one  dorsal.  Thus 
there  is  a  regular  alternation  of  section-walls  with  a  halving  of  the  mar- 
ginal cells.  At  least  six  or  seven  section-walls  are  formed  in  the  region 
which  is  to  become  petiole  or  rachis.  The  ultimate  marginal  cell  is  then 
cut  across  by  a  periclinal  wall  (figs.  142,  143).  Its  specific  activity  is  ended 
and  its  outer  portion  breaks  up  into  epidermal  cells.  The  relation  of  the 
sections  to  the  inner  tissues  of  the  petiole  and  rachis  (vascular  tissues,  etc.) 
differs  in  different  places,  and  was  not  worked  out  in  detail. 

No  sooner  has  the  leaf-rudiment  become  a  conical  projection  on  the  stem 
than  it  begins  to  grow  more  actively  on  the  dorsal  side — to  bend  over 
toward  the  stem-initial — to  become  circinate.  The  initial  cell  of  the  leaf 
lies  with  one  point  (in  cross  section)  towards  the  stem  initial  and  the  ven- 
tral (upper)  surface  of  the  leaf,  the  other  point  in  the  dorsal  (lower)  surface 
of  the  leaf. 

The  circinate  vernation  comes  about  through  the  rapid  growth  in  thick- 
ness of  the  dorsal  sections  of  the  segments.  The  cells  divide  about  twice 
as  rapidly  as  in  the  ventral  sections,  and  are  larger  (figs.  136,  139).  A 
little  later,  divisions  occur  on  the  ventral  side  to  about  the  number  of  those 
on  the  dorsal,  but  the  curved  position  is  maintained  by  greater  elongation 
of  the  dorsal  cells.  Finally,  when  the  leaf  unfolds,  the  ventral  cells  elongate 
to  equal  those  of  the  dorsal  surface. 

The  activity  of.  the  initial  cell  of  the  leaf  is,  as  in  most  ferns,  limited. 
After  the  rudiments  of  five  to  eight  pairs  of  pinnae  are  visible  and  about 
three  pairs  of  segments  are  cut  off  in  advance  of  any  visible  differentiation 
into  pinnae,  the  initial  ceases  to  exist  as  such.  Probably  it  simply  begins 
to  divide  into  sections  as  a  segment  would  do.  Fig.  138  shows  a  leaf-tip 
at  this  stage,  where  the  initial  has  divided  twice  in  succession  on  the  same 
side.  There  is  no  evidence  at  all  for  a  "transverse"  division  of  the 
initial.  After  the  initial  is  lost  the  leaf -apex  is  occupied  by  a  group  of 
marginal  cells  (figs.  137,  144)  which  grow  and  section  and  divide  into 
halves  for  a  long  time.  Since  it  is  probable  that  each  segment  of  the 
initial  (while  it  lasts)  develops  a  single  pinna  in  the  region  of  the  lamina, 
we  may  say  that  the  lowest  eight  to  eleven  pairs  spring  from  as  many 


SPOROPHYTE.  31 

segments.  The  remaining-  22  to  40  pairs  of  pinnae  come  out  after  the 
single  initial  is  lost.  In  either  case  their  actual  history  is  the  same. 

The  apical  growth  of  the  leaf,  with  or  without  a  single  initial,  gives 
rise  directly  to  a  slightly  flattened  and  circinately  curved  rod  of  embryonic 
cells  (figs.  140,  141,  144).  Each  margin  is  occupied  by  a  row  of  marginal 
cells  (fig.  137).  Where  a  pinna  is  to  develop,  about  six  consecutive 
marginal  cells  elongate  to  form  a  papilla.  By  sectioning"  and  halving  they 
rapidly  increase  in  number  of  cells  and  mass  of  tissue.  The  apex  of  the 
papilla  and  its  manner  of  growth  are  exactly  like  those  of  the  tip  of  the 
leaf  after  the  loss  of  the  initial  cell  (figs.  145-147).  On  the  sides  of  this 
protuberance  similar  outgrowths  form  the  pinnules,  and  on  the  pinnules, 
in  a  similar  manner,  the  lobes  of  the  pinmile  arise,  and  on  these  again,  in 
like  manner,  the  ultimate  crenations  of  the  leaf -margin  (figs.  5,  148,  149). 
From  the  inner  ends  of  the  oldest  sections  in  each  part  of  the  leaf  the 
vasctilar  tissues  are  derived  (fig.  149).  In  every  case  also  there  are  in- 
active marginal  cells  between  those  groups  which  grow  out  to  form  pinnae, 
pinnules,  lobes,  alid  teeth.  These  sluggish  cells  ultimately  give  rise  to 
the  tissues  along  the  rachis  between  the  pinnae,  or  along  the  ribs  between 
the  pinnules,  or  in  the  notches  of  the  pinnules  (fig.  148).  In  the  lamina 
proper,  away  from  any  vein,  the  sections  of  the  marginal  cell  are  broad 
and  shallow,  extending  only  half  the  thickness  of  the  leaf  (fig.  150).  Each 
of  the  sections  is  halved  parallel  to  the  surface  of  the  leaf.  The  outer  half 
is  an  epidermal  cell;  the  inner  half  remains  single  or  divides  again  in  the 
same  plane  and  forms  parenchyma  (fig.  150).  The  ultimate  marginal 
cells  constitute  the  margin  of  the  mature  leaf.  Stomata  are  formed  while 
the  epidermal  cells  are  still  polygonal  in  outline,  and  while  the  leaf  is  un- 
folding. A  curved  wall  cuts  out  the  stoma  mother-cell  on  one  side  of  a 
young  epidermal  cell  (figs.  152,  153).  The  mother-cell  becomes  oval  and 
is  divided  longitudinally  into  the  two  guard-cells. 

With  20  to  25  pairs  of  rudimentary  pinnae,  no  stomata,  no  air-spaces  in 
the  parenchyma,  and  no  signs  of  fructification,  the  leaves  emerge  from 
the  soil.  It  would  be,  therefore,  quite  a  mistake  to  suppose  that  in  Denn- 
stccdtia  Punctilobula  the  unfolding  of  the  leaves  "consists  merely  in  an  ex- 
pansion of  the  leaf  with  comparatively  little  cell  division' '  (Campbell,  1895, 
p.  325;  1905,  p.  333),  in  spite  of  the  rapidity  with  which  the  unfolding 
takes  place.  One-third  to  one-half  of  the  blade  of  the  leaf  must  be  made 
outright  during  this  time.  In  eastern  Pennsylvania  and  Maryland  the  leaves 
appear  above  ground  in  the  latter  half  of  April  (Cockeysville,  Maryland, 
April  21;  Oxford  Valley,  Pennsylvania.,  April  29,  1905).  By  June  4  (Loch 
Raven,  Maryland,  1905)  spores  are  nearly  mature.  At  first  the  petioles, 
green  in  all  the  aerial  part  and  clothed  with  white  hairs,  elongate  and  unroll. 
Then  the  leaf  spreads  out  from  below  upward .  A  comparison  of  figs .  2  and  5 
of  the  mature  leaf  and  fig.  152  of  a  pinnule  3  mm.  long  from  an  unrolling 
leaf  will  give  an  idea  of  the  change  that  goes  on.  In  fig.  152  the  stomata 


32  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

are  just  developing-.  The  pinna  from  which  this  was  taken  was  1.5  cm. 
long,  and  unrolling". 

While  it  is  unfolding-  (May  4,  1906,  Baltimore,  Maryland),  the  fertile  leaf 
acquires  its  sori.  In  origin  the  sori  are  strictly  marginal.  At  the  point 
where  a  sorus  is  to  develop,  a  marginal  cell  of  the  lamina,  at  the  tip  of  a 
rudimentary  veinlet,  after  giving  rise  to  a  mass  of  vein  and  lamina  cells, 
grows  out  into  a  short,  rounded  papilla  (fig's.  151,  158;  cf.  also  fig-.  63 D  in 
Sadebeck,  1898).  This  papilla  is  the  rudiment  of  the  first  and  central  spo- 
rangium. Neighboring-  cells  elong-ate  to  form  a  mound,  the  placenta.  New 
sporangia  at  once  beg-in  to  develop  around  the  first  one.  Meanwhile,  about 
four  or  five  cells  removed  from  the  central  marginal  cell,  the  leaf -tissues 
beg-in  to  rise  up  in  a  ring-  (indusium)  around  the  placenta  (fig.  158).  The 
ventral  (upper)  part  of  this  ring  soon  becomes  much  thicker  than  the 
opposite  side — as  thick,  indeed,  as  the  lamina  itself.  Vascular  tissues,  also, 
are  formed  for  a  short  distance  into  this  lobe  (fig.  155). 

As  growth  proceeds,  the  sorus  reaches  its  ultimate  position  on  the  under 
side  of  the  leaf.  One  is  found  on  the  lower  outer  venule  of  each  lobe  of 
each  pinnule  (fig.  5).  At  maturity  the  indusium  is  circular  and  cup- 
shaped.  One  side  of  it  is  contimums  with  the  margin  of  the  leaf  (fig.  155); 
elsewhere  it  rises  abruptly  from  the  surface.  In  its  lower  parts  it  con- 
sists of  inner  and  outer  epidermis,  with  a  few  parenchyma  cells  and  air- 
spaces between.  Here  stomata  occur  both  within  (fig.  120)  and  without 
(fig.  119).  The  epidermal  cells  are  wavy-margined  (fig.  115).  The 
indusium  tapers  above  to  two  cells,  then  to  one  cell  in  thickness.  On  its 
sides  and  margin  it  bears  hairs,  both  glandular  and  acicular.  The  margin 
is  irregular.  In  the  bottom  of  the  indusium  cup  and  on  the  side  nearest 
to  the  base  of  the  pinnule  is  a  low,  rounded  placenta.  It  is  covered  with 
epidermis,  beneath  which  is  a  layer  of  parenchyma,  and  then  a  group  of 
short  scalariform  tracheids  (fig.  155).  These  last  constitute  morphologic- 
ally the  end  of  the  neighboring  venule,  which  appears  to  terminate  under 
the  sorus  just  beyond  \he  placenta.  The  apparent  ending  is  really  a  branch 
in  the  indusium.  From  the  placenta  arise  a  few  paraphyses  (figs.  169, 
173)  and  a  number  of  sporangia.  The  paraphyses  are  obtuse  hairs,  com- 
posed of  about  three  cylindrical  cells  each. 

The  sporangia  arise  in  centrifugal  succession  from  superficial  cells  of 
the  placenta.  The  mother-cell  bulges  out  considerably  and  is  cut  by  an 
obliqtie  wall  from  the  middle  of  its  base  to  one  side  of  its  summit  (fig. 
159).  A  second  oblique  wall  strikes  across  from  one  side  of  the  summit 
to  the  first  wall  (fig.  160).  A  third  wall,  striking  both  of  the  preceding, 
leaves  an  upper  cell  with  a  spherical  outer  surface  and  a  triangular  pyra- 
midal base.  Three  more  divisions  follow  in  the  upper  cell,  parallel  to  the 
first  three  (fig.  157).  Then  a  transverse  wall  cuts  across  the  top,  leaving 
a  central  tetrahedral  cell  (the  primitive  archesporium)  surrounded  by  four 
wall-cells  (figs.  154,  156).  The  three  lowest  and  earliest-formed  cells 


SPOROPHYTE.  33 

divide  only  transversely,  and  give  rise  to  the  three  rows  of  cells  of  the 
stalk  (figf.  176).     The  four  wall-cells  form  the  walls  of  the  sporangium. 

The  archesporial  cell  at  once  cuts  off  four  tapetal  cells  (fig's.  161,  162), 
one  on  each  of  its  faces,  beginning-  on  the  sides.  Each  tapetal  cell  divides 
into  four  by  anticlinal  walls.  The  archesporial  cell  then  divides  nearly 
vertically  into  two,  and  the  tapetum  divides  periclinally  into  two  layers 
(fig-.  163).  The  exact  relation  in  time  of  the  divisions  of  archesporium 
and  tapetum  is  not  constant  (fig's.  164,  166).  From  this  time  onward  the 
archesporial  cells  divide  exactly  synchronously,  though  in  different  planes, 
first  into  four  (figs.  165,  166),  then  into  eig-ht,  and  finally  into  sixteen. 
As  soon  as  the  sixteen  spore  mother-cells  are  formed  the  tapetum  begins  to 
degenerate  (figs.  167,  170).  Its  walls  dissolve,  and  the  cytoplasm  forms 
a  vacuolated  mass,  but  the  nuclei  persist  until  the  spores  are  acquiring 
their  definite  walls  (fig.  168).  The  spore  mother-cells,  at  first  in  a  solid 
mass  (fig.  167),  enlarge  rapidly  and  separate  from  one  another.  Their 
nuclei  especially  increase  to  a  relatively  great  size  (fig.  170).  The  chro- 
matin  now  lies  in  innumerable  fine  granules.  Then  a  long,  fine,  and 
tangled  chromatin  thread  is  organized,  and  synapsis  ensues.  This  must 
be  a  lengthy  stage,  as  it  is  frequently  and  easily  found.  Emerging  from 
synapsis,  a  heterotypic  division  occurs.  The  two  resulting  nuclei  at  once 
divide  again,  and  spindle  fibers  are  formed  between  all  four  of  the  daughter 
nuclei.  Across  the  fibers  cell- walls  are  laid  down.  The  spores  remain 
together  in  fours  until  their  walls  are  thickened.  They  separate  before 
the  final  sculpturings  are  formed  on  the  outside.  Thus  the  spores  always 
show  a  tetrahedral  angle.  The  sculpturings  are  irregular  lines  and  lumps 
of  brown  substance  (figs.  174,  175).  All  stages  in  the  formation  of 
sporangia  and  spores  may  be  found  in  a  single  collection  of  material  from 
newly  unfolded  fronds  (e.  g.,  Loch  Raven,  Maryland,  at  base  of  a  steep  hill 
facing  north,  June  4,  1905).  Meanwhile  the  wall  of  the  sporangium  has 
also  reached  its  mature  size  and  structure.  The  sides  consist  of  very  thin, 
broad  cells,  about  eleven  on  each  side.  The  right  and  left  sides  are  nearly 
identical  (figs.  171,  172).  The  annulus  runs  from  the  stalk  up  one  edge 
and  over  the  top  of  the  sporangium  and  about  one-quarter  of  the  way 
down  the  other  edge.  Its  cells,  18  or  19  in  number,  are  cubical  and 
are  heavily  lignified  on  all  except  the  outer  walls.  The  mouth  of  the 
sporangium,  or  point  of  rupture,  lies  between  two  long,  narrow,  slightly 
thickened  cells  (sometimes  two  such  cells  on  one  or  the  other  lip)  about 
midway  between  the  end  of  the  annulus  and  the  stalk.  Similar  long,  narrow 
cells,  three  to  five  in  number,  but  with  thin  walls,  fill  up  the  space  above 
and  below  the  mouth.  At  maturity  the  whole  sporangium  and  contents 
dry  out,  and  the  spores  are  hurled  away  as  described  for  another  fern  by 
Atkinson  (1894).  The  annulus  tends  to  straighten,  and  it  does  so,  slowly 
opening  the  mouth  of  the  sporangium  and  tearing  the  walls  nearly  straight 
across  their  whole  width.  It  bends  far  around  backward  until  the  head 


34  STRUCTURE    AND    LIFE-HISTORY    OF    HAY-SCENTED    FERN. 

of  the  sporangium  nearly  touches  the  stalk.  Meanwhile  some  spores  have 
fallen  out,  others  remain  in  each  half  of  the  sporangium.  Then  suddenly 
the  annulus  springs  back  to  its  former  place,  throwing  its  load  of  spores 
several  centimeters.  Straightway  it  begins  slowly  to  bend  back  again, 
and  repeats  the  operation.  The  springing  of  the  thin  walls  during  both 
the  extension  and  the  recoil  of  the  annulus  throws  out  several  spores. 

GAMETOPHYTE. 

Spores  sown  on  moist  micaceous  earth  about  Octobers,  1905,  had  mostly 
germinated  and  formed  protonemata  by  the  25th.*  About  October  1, 
1905,  also,  fresh  male  and  female  prothallia  and  young  plants  in  various 
stages  of  development  were  found  in  a  ravine  near  Baltimore,  Maryland. 
In  germination  the  spore-coat  bursts  at  the  tetrahedral  angle.  The  intine 
bulges  out,  and  a  cell  with  many  chloroplasts  appears  (fig.  177).  It  imme- 
diately sends  out  a  rhizoid  which  is  separated  by  a  wall  from  the  cell. 
Some  of  my  cultures  became  temporarily  dry  at  this  stag'e,  and  the  first 
rhizoid  died.  Another  was  soon  sent  out  from  a  point  farther  up  on  the 
same  cell  (figs  .191,193).  The  protonemata  assumed  a  great  variety  of  shapes 
(figs.  178-199).  There  were  from  one  to  six  cells,  in  linear  series.  The 
basal  cell  was  sometimes  very  long  and  slender  (figs.  184,  196),  or  rarely 
broader  than  long  (fig.  182).  The  basal  cell  was  usually  the  longest  of  all, 
but  not  always  (fig.  197).  The  growth  of  the  protonema  is  by  transverse 
divisions  in  the  apical  cell.  Rarely  an  intercalary  division  occurs  in  a 
longitudinal  plane. 

Sooner  or  later  the  terminal  cell  divides  longitudinally  in  half  (fig.  189). 
One  half  enlarges  more  than  the  other,  causing  the  partition  to  become 
oblique.  Then  an  oblique  wall  cuts  the  larger  cell,  striking  the  next 
earlier  wall  nearly  at  right  angles  (figs.  185,  196).  The  result  is  a  two- 
sided  apical  cell,  which  continues  to  divide  parallel  to  its  two  sides  for  a  long 
time  (figs.  187,  188,  190).  The  young  gametophyte  now  becomes  broader 
at  the  apex  (figs.  194,  195).  Soon  the  cells  on  either  side  of  the  initial 
outgrow  those  just  behind  it,  and  the  prothallus  assumes  its  cordate  shape 
(figs.  199,  200).  The  initial  is  then  changed  by  a  transverse  wall  across 
its  posterior  end  (fig.  203).  After  this  it  divides  into  two  longitudinally, 
and  we  can  henceforth  recognize  only  a  group  of  marginal  initials  (fig. 
200).  Each  of  these  cells  divides  on  three  sides,  viz,  two  lateral  and  one 
posterior  (figs.  202,  204-207,  214). 

*My  cultures  were  sown  in  3-inch  to  6-inch  flower-pots  and  pans  on  micaceous  soil 
dug  from  deep  down  in  a  newly  exposed  bank  of  earth.  Ripe  leaves  were  laid  on  the 
pots,  covered  loosely  with  papers,  and  allowed  to  dry  and  shed  their  spores.  Or,  the 
de'bris  of  dried  fertile  leaves  was  sown.  The  pots  and  pans  were  never  sprinkled,  but 
were  kept  standing  in  i  to  2  cm.  of  water,  covered  with  glass  plates,  before  a  west 
window  of  the  Johns  Hopkins  Biological  Laboratory. 


GAMETOPHYTE.  35 

Meanwhile  many  rhizoids  are  reaching-  from  the  under  surface  of  the 
prothallus  into  the  earth  (fig-.  231).  Hitherto  all  of  the  divisions  men- 
tioned have  been  vertical,  and  there  is  but  one  layer  of  cells.  When,  as 
in  female  plants,  a  "cushion"  is  formed  in  the  middle  of  the  prothallus, 
divisions  parallel  to  the  surface  occur  in  the  posterior  segments  of  the 
initials  (figs.  202,  205-207,  214).  The  upper  half  of  the  segment  may 
divide  once  or  twice  in  this  plane,  giving-  rise  to  two  or  three  layers  of 
cells.  The  lower  half  is  responsible  for  most  of  the  bulk  of  the  cushion 
and  for  all  of  the  organs  which  appear  thereon  (figs.  206,  207).  In 
crowded  cultures  wart-like  outgrowths  occur  on  the  upper  surface  of  the 
prothallus  (fig.  201).  They  can  only  be  considered  as  abnormalities. 

The  prothallia  reach  sexual  maturity  at  five  weeks  and  later  from  sowing 
of  spores.  They  are  practically  always  dioecious.  Only  three  hermaph- 
rodites have  I  seen.  On  one  of  these  male  and  female  organs  seemed  to 
be  mature  at  the  same  time.  The  males  mature  first,  and  they  may  con- 
tinue to  grow  and  bear  great  numbers  of  antheridia  for  five  months  or 
more.  Antheridia  may  appear  on  very  small  plants.  I  found  one  in  a  glen 
near  Baltimore,  Maryland,  in  which  there  were  four  prothallial  cells  and 
three  antheridia  (fig.  198).  All  sizes  and  shapes  occur  from  this  up  to 
those  which  are  5  mm.  across,  with  many  lobes,  and  the  margins  crisped  like 
a  "curly"  lettuce-leaf.  Whether  those  which  bear  sexual  organs  at  a  very 
early  age  ever  develop  to  large  size  I  do  not  know.  Probably  they  do  not. 

The  male  prothallus  is  always  but  one  cell  thick;  it  has  no  cushion. 
The  antheridia  arise  at  any  point  on  the  shaded  side— central  or  marginal 
(figs.  227,  228).  In  large  "curly"  specimens  the  relation  to  light  is 
clearly  shown.  A  section  may  show  an  S-shaped  portion  of  prothallus. 
Supposing  the  light  to  come  from  the  upper  edge  of  the  page,  the  anthe- 
ridia will  be  found  on  the  lower  side  of  each  transverse  bar  of  the  S. 
Two  of  these  will  be  the  morphologically  lower  surface  and  one  the  upper. 
At  transition  points  two  antheridia  may  be  seen  on  opposite  sides  of  the 
same  cell ! 

The  antheridium  arises  from  the  prothallial  cell  as  a  papilla,  which  is 
soon  cut  off  by  a  basal  wall  (fig.  225).  It  differs  in  appearance  from  a 
young  rhizoid  in  having  many  chloroplasts,  though  the  rhizoid  rudiment 
may  have  two  or  three.  In  preserved  material  this  difference  is  not  evi- 
dent. The  papilla  enlarges  and  is  cut  in  two  by  another  wall  parallel  to 
the  first  (fig.  226).  The  first  cell  is  the  stalk-cell,  and  undergoes  no 
further  division;  the  other  is  the  antheridial  mother-cell.  The  next  two 
walls  are  those  commonly  described  for  fern  antheridia,  viz,  first  a  dome- 
shaped  wall  parallel  to  the  outer  wall  of  the  mother-cell  (figs.  228,  232); 
second,  a  circular  wall  at  the  summit  of  the  outer  cell  to  form  the  lid. 
The  body  of  the  antheridium  now  consists  of  a  cylindrical  wall-cell,  a  cir- 
cular cap-cell,  and  a  large,  dense  central  cell.  The  central  cell  is  devoid 
of  chlorophyll.  It  divides  at  first  vertically  (fig.  227),  then  in  three 


36  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

planes  at  right  angles  to  one  another,  and  at  last  irregtilarly  (fig.  230),  to 
produce  32  sperm  mother-cells.  These  separate  and  round  off,  and  in 
each  one  a  spiral  spermatozoid  develops.  As  the  central  mass  enlarges  it 
pushes  itself  down  into  the  center  of  the  stalk-cell  until  it  reaches  the 
original  basal  wall  (figs.  230,  237).  Thus  the  stalk-cell  becomes  ring- 
shaped,  though  at  first  it  was  a  disk  (figs.  226,  229).  At  maturity  the 
contents  of  the  antheridium  swell  up  by  absorption  of  water,  the  cap-cell 
is  ruptured  irregularly,  and  the  sperm  mother-cells  escape.  After  45  to 
50  seconds  the  mother-cell  wall  bursts  and  the  spermatozoid  swims  rapidly 
away  with  a  steady  rotary  motion,  bearing  a  granular  vesicle  at  the  pos- 
terior end.  From  cultures  of  male  prothallia  kept  free  from  surface-water 
it  is  easy  to  get  numbers  of  spermatozoids  by  mounting  the  prothallia  in 
water.  Mr.  W.  D.  Hoyt  found  them  to  be  distinctly  attracted  by  a  malic- 
acid  solution  of  suitable  strength.  The  body  of  the  sperm  makes  about 
two  and  a  half  coils.  The  anterior  end  is  more  slender  and  more  closely 
coiled. 

TABLE  7. — Development  of  antheridium. 

<Pro.thallial  cell 
.Stalk  cell 
Antheridial  cell(  /dome-like  ^walfcell 

Body  cefl{  outer  cell  )^  cover  cell 

inner  cell — 32  sperm  mother  cells 

Female  prothallia  are  always  cordate  in  shape  and  bear  their  archegonia 
on  the  under  side  of  a  central  thickening  or  cushion.  They  begin  to  form 
sexual  organs  when  still  narrower  than  long,  five  or  six  weeks  from  sow- 
ing of  spores.  If  not  fecundated  they  continue  to  grow  larger  and  broader, 
and  produce  many  archegonia  in  succession  over  all  the  central  lower  sur- 
face. The  upper  surface  is  at  first  flat,  but  in  old  females  the  margins 
may  become  reflexed  dorsally,  and  the  plant  forms  a  broad,  erect  funnel, 
open  on  one  side.  The  largest  in  my  cultures  are  5  to  7  mm.  tall  and  6 
to  9  mm.  across.  I  found  one  out  of  doors  7  mm.  wide  and  4  mm.  long. 

The  archegonium  develops  from  a  cubical  superficial  cell  of  the  pro- 
thallus, near  to  the  initial  cells.  This  cell  may  be  a  semi-segment,  involv- 
ing half  the  thickness  of  the  prothallus  (fig.  202),  or  it  may  be  simply 
the  outer  part  of  a  semi-segment  (figs.  206,  214),  according  to  its  point  of 
origin  on  the  prothallus  and  the  size  and  thickness  of  the  latter.  In  any 
case  the  definitive  archegonial  mother-cell  first  cuts  off  a  thin  superficial 
cell,  the  neck  rudiment  (fig.  202).  Then  on  the  opposite  side  a  similar 
basal  cell  is  separated,  leaving  a  large  central  cell  (figs.  206,  207).  The 
basal  cell  divides  crosswise  into  four  and  forms  the  innermost  part  of  the 
wall  of  the  archegonium  (fig.  208).  The  neck  rudiment  similarly  divides 
crosswise  into  four  (fig.  207).  Its  first  cleavage  wall  is  parallel  to  the 
longitudinal  axis  of  the  prothallus.  Now  the  central  cell  enlarges  and 
pushes  out  the  four  neck-rudiments.  As  the  latter  project  more  and  more 


GAMETOPHYTE.  37 

from  the  surface  of  the  cushion  they  divide  each  into  a  row  of  cells  (fig's. 
208-213).  The  neck,  therefore,  consists  of  four  rows  of  cells  (figs.  213, 
220-222),  two  anterior  and  two  posterior.  The  divisions  always  occur  in 
the  uppermost  or  next  to  uppermost  members  (fig-.  210).  At  maturity 
the  neck  bends  over  strongly  away  from  the  growing-  point  of  the  pro- 
thallus  (fig's.  207,  211,  219).  In  relation  to  this  we  find  in  each  of  the  two 
rows  of  cells  of  the  neck  on  the  convex  side  two  cells  more  than  on  the 
concave  side  (4  and  6,  or  5  and  7). 

Meanwhile  the  central  cell  has  cut  off  a  "neck  canal-cell"  (fig's.  209, 
210),  which  pushes  up  in  the  axis  of  the  neck.  It  acquires  two  nuclei 
(fig-.  215),  rarely  three  (fig-  218).  Another  division  in  the  central  cell 
cuts  off  the  "ventral  canal-cell,"  lying-  at  the  base  of  the  neck  (fig's.  216, 
217,  218).  The  largfe  remainder  is  the  eg-g--cell.  As  the  archeg-onium 
matures  the  neck  enlargfes  and  becomes  swollen  near  the  end  (fig-.  219). 
The  canal-cells  deg-enerate  into  an  amorphous  mass,  the  central  parts  of 
which  stain  deeply  with  haematoxylin.  At  this  time  also  a  distinct  venter 
wall  is  formed  around  the  egg  by  divisions  in  all  the  prothallial  cells  sur- 
rounding- it  (figs.  219,  223,  224).  To  recapitulate,  the  archeg-onium  as  a 
whole  is  made  up  from  two  sources — the  neck,  canal-cells,  egg,  and  four 
basal  cells  of  the  venter  are  all  derived  from  the  original  cubical  arche- 
g-onium mother-cell;  the  side  walls  of-  the  venter  are  derived  from  all  the 
neighboring-  prothallial  cells. 

TABLE  8. — Development  of  archegonium. 

neck  cell 4  neck  cells-4  rows  of  neck  cells 

Mother   / 

cell      \  /neck  canal  cell;- neck  canal  cell,  2  or  3  nuclei 

interior  cell-^- central  cell/ 

\  /ventral  canal  cell 

central  cell<" 

ovum 

sal  cell— 4  basal  cells — base  of  venter  wall 
Surrounding  cells  of  prothallus  form  side  walls  of  venter. 

When  the  archegonium  is  wholly  mature,  the  uppermost  four  or  eigfht 
neck-cells  break  apart,  leaving-  a  wide-open  mouth  (figs.  220,  224). 
Through  this  a  transparent  mucilaginous  substance  exudes,  and  may 
stream  out  for  a  distance  several  times  the  length  of  the  archegonium 
(fig.  224).  In  this  substance  spermatozoids  gather  in  great  numbers. 
As  a  sperm  enters  the  mucilage  its  movements  become  slower,  and  it 
changes  from  a  short,  stout  helix  to  a  long,  slender  one  with  more  turns. 
The  vesicle  attached  to  its  posterior  end  is  twisted  off  by  the  resistance  of 
the  mucilage  and  floats  away.  The  sperms  swarm  into  the  neck  and 
make  their  way  down  towards  the  egg,  which  becomes  pointed  as  though 
reaching  out  to  receive  them  (fig.  223).  The  lower  part  of  the  neck  is  so 
constricted  (fig.  222)  that  the  sperms  have  to  become  nearly  straight  to 
get  through,  but  many  succeed  in  doing  so. 


38  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

The  remains  of  unsuccessful  sperms  are  left  after  fecundation  as  a  deeply- 
staining-  cap  over  the  top  of  the  egg-cell.  The  fertilized  egg  rounds  off 
and  comes  to  rest,  with  a  large  central  nucleus  and  nucleolus  (fig.  224). 

About  half  of  the  mature  prothalli,  with  apparently  perfect  archegonia, 
will  actually  be  fertilized  when  mounted  on  a  slide  with  mature  males.  In 
such  cases  not  only  is  the  receptive  archegonium  filled  with  sperms,  but 
many  older  archegonia,  up  to  a  dozen  on  a  single  plant,  including  such  as 
are  brown  with  age,  are  quite  as  eagerly  crowded  into  by  numbers  of 
sperms.  Only  once,  however,  have  I  known  two  embryos  to  appear  on 
one  prothallus.  Young  archegonia  continue  to  develop  on  the  fertile 
prothallus  for  a  time.  But  after  the  embryo  is  fully  established  (i.e., 
octant  stage),  sexual  organs  cease  to  develop.  Fertilized  eggs  were  found 
about  7  days  after  my  cultures  had  been  flooded  with  water.  In  16  days 
many  embryos  were  visible  with  a  hand-lens. 

THE  YOUNG  SPOROPHYTE. 

The  first  cleavage-plane  (basal  wall)  in  the  fertilized  egg  includes  the 
axis  of  the  archegonium,  and  lies  transversely  to  the  axis  of  growth  of  the 
prothallus.  It  divides  the  egg  into  anterior  and  posterior  halves  (see 
below).  The  second  (quadrant)  wall  passes  horizontally  and  at  right 
angles  to  the  axis  of  the  archegonium.  In  each  quadrant,  then,  a  vertical 
wall  is  formed  at  right  angles  to  the  two  preceding,  dividing  the  embryo 
into  octants.  These  octant  walls  do  not  correspond  in  the  different  quad- 
rants, but  the  octants  are  from  the  first  unequal  in  size  (figs.  233,  234). 
Supposing  the  prothallus  to  lie  before  the  observer  with  cushion  down- 
ward and  the  notch  on  the  farther  side,  we  may  speak  of  right  and  left, 
anterior  and  posterior,  upper  and  lower  portions.  The  fate  of  the  octants 
may  be  stated  thus: 

i.  Anterior  upper  right  octant=Stem  initial 


.   .  ,  or  -vice  versa. 

2.  Anterior  upper  left  octant   —Irregular 

3.  Anterior  lower  right  octant  =   ) 

4.  Anterior  lower  left  octant       =   J  F 

5.  Posterior  upper  right  octant  =   [ 

6.  Posterior  upper  left  octant  =   j 

7.  Posterior  lower  right  octant=Irregular  )  Qr  ^^  versa>. 

8.  Posterior  lower  left  octant  =Root         j 

It  must  not  be  supposed,  however,  that  this  arrangement  is  invariable. 
On  a  prothallus  with  two  embryos  one  has  the  root-intitial  in  octant  8,  the 
other  in  7.  Octants  2,  3,  5,  7  are  smaller  than  1,  4,  6,  8.  The  first 
division  in  2,  4,  6,  8  is  parallel  to  the  basal  wall  and  near  to  it.  In  8 
the  succeeding  divisions  are  parallel  to  the  other  primary  walls,  and  then 
to  the  curved  outer  wall.  The  resulting  tetrahedral  central  cell  is  the 
root  initial.  It  continues  to  divide  in  the  way  which  is  characteristic  for 
roots  (?.  v.)  (figs.  235,236). 


THE   YOUNG   SPOROPHYTE.  39 

The  two  posterior  upper  octants  (5,6)  divide  irregularly  into  a  mass  of 
polyhedral  cells,  the  foot.  Those  in  contact  with  the  base  of  the  arche- 
g-onium  become  closely  applied  to  the  wall,  and  the  boundary  between 
prothallial  and  embryonic  tissues  is  often  difficult  to  determine.  Neigh- 
boring- cells  of  the  two  anterior  upper  octants  are  also  involved  in  the  for- 
mation of  the  fully  matured  foot  (figfs.  235,  236,  246). 

Octants  2  and  7  divide  irreg-ularly  and  serve  only  to  fill  up  their  respec- 
tive corners  of  the  embryo  plant.  Octant  1,  after  cleavag-es  mostly  parallel 
to  the  basal  and  quadrant  walls,  ultimately  gives  rise  to  the  stem-initial, 
lying:  close  to  the  octant  wall,  /.  <?.,  near  the  median  line. 

The  lower  anterior  octants  (3  and  4)  elong-ate  tog-ether  in  a  horizontal 
direction  (fig-.  255).  They  unite  at  their  anterior  ends  to  form  a  group  of 
marginal  initials  for  the  first  leaf  (cotyledon).  This  leaf,  therefore,  never 
possesses  a  single  apical  cell. 

As  the  leaf  grows  out,  the  whole  anterior  (epibasal)  half  of  the  embryo 
elong-ates,  carrying-  forward  both  stem-initial  and  leaf.  The  plantlet  lies 
horizontally.  It  consists  of  a  short  cylinder  with  root-initial  at  one  end, 
leaf -initials  at  the  other  end,  a  dorsal  papilla  near  the  middle,  in  which  is 
the  stem-initial,  and  back  of  this  a  large  dorsal  protuberance,  the  foot, 
buried  in  the  prothallus  (figf.  246) .  The  whole  is  surrounded  by  the  greatly 
enlarg-ed  archegfonial  wall,  the  calyptra.  The  latter  has  become  two  or 
three  cells  thick  all  round  (fig's.  246,  255).  Soon  the  leaf  bursts  throug-h 
the  calyptra  and  bends  upward  throug-h  the  notch  of  the  prothallus,  and 
the  primary  root  extends  downward.  The  new  plant  is  now  independent, 
but  the  prothallus  does  not  disappear  until  two  or  three  leaves  are  formed 
(fig.  267). 

The  youngf  stem  grows  almost  horizontally  for  1  or  2  mm.,  increasing- 
in  diameter  and  complexity  of  structure  until  about  five  leaves  have  been 
formed.  The  stem  then  forks.  The  plant  now  differs  only  in  size  and 
sterility  from  the  adult.  The  primary  root  grows  about  5  cm.  long,  is 
slender,  and  has  the  structure  of  an  adult  rootlet  (q.  v.).  It  is  not 
branched,  but  has  copious  root-hairs.  Adventitious  roots  arise  in  rapid 
succession,  being"  sometimes  as  many,  sometimes  twice  as  many,  as  the 
leaves  (figf.  256).  They  are  like  adult  roots,  only  smaller.  I  have  one 
specimen  whose  root-cells  are  densely  filled  with  fungfous  hyphae,  after  the 
manner  of  the  adult  mycorhiza.  The  prothallus  is  also  infected,  but  there 
is  no  connection  (internally  at  least)  between  the  fungous  masses  in  sporo- 
phyte  and  gfametophyte. 

The  sporelingf  stem  is  short  and  cylindrical  (fig~iire  269).  It  is  clothed 
with  an  irregular  epidermis.  The  cortex,  parenchymatous  below,  mergfes 
gradually  into  that  of  the  adult  region.  The  stele  of  the  primary  root  is 
continuous  with  that  of  the  stem.  There  is  no  line  of  demarcation  on  the 
ventral  side,  but  dorsally  a  prominent  angle  of  vascular  tissue  projects 
toward  the  foot  (fig's.  246,  247).  Between  this  point  and  the  insertion  of 


40  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

the  first  leaf  the  stem  is  protostelic.  It  contains  a  solid  core  of  scalariform 
tracheids  (xylem),  surrounded  in  succession  by  conjunctive  parenchyma, 
phloem,  pericycle,  and  endodermis  (fig.  238).  At  the  exit  of  the  first 
leaf-trace  there  is  a  depression  containing:  parenchyma  on  that  side  of  the 
xylem  (fig.  239).  Farther  up  the  xylem  extends  around  so  as  to  inclose 
this  parenchyma.  In  the  parenchyma,  even  before  the  exit  of  the  second 
leaf -trace,  phloem  and  conjunctive  parenchyma  may  be  recognized  (fig-. 
240).  The  second  leaf  makes  a  similar  gap  in  the  xylem.  Between  the 
second  and  third  leaf-gaps  there  appears  in  the  midst  of  the  central  phloem 
a  group  of  large  cells  identical  in  appearance  with  the  outer  pericycle  (fig. 
241 ,  ip) .  At  the  exit  of  the  third  leaf -trace  the  outer  pericycle  becomes 
continuous  with  the  central  tissue  just  mentioned,  through  a  gap  in  the 
xylem  and  phloem  (fig.  256).  The  gap  closes  again  without  any  dipping 
in  of  the  endodermis.  Below  the  fourth  leaf  there  appears  a  thickened 
band  (Caspary's  band)  on  the  cross  wall  between  two  parenchyma  cells  at 
the  center  of  the  stele  (fig.  242).  In  the  next  section  (10  /*  higher)  there 
is  a  line  of  five  cells  whose  intermediate  walls  bear  the  thickened  band 
characteristic  of  endodermis  (fig.  243).  Two  sections  higher  (20  /*)  there 
is  a  ring  of  endodermis  at  the  center  of  the  stele,  inclosing  one  scleren- 
chyma  cell  (fig.  244).  The  ring  enlarges  rapidly  and  parenchyma  cells 
appear  beside  the  sclerenchyma  (fig.  245).  The  solenostelic  structure  is 
established.  The  fourth  leaf -gap  is  like  the  third,  with  only  a  very  slight 
dipping  inward  of  the  outer  endodermis  (fig.  257).  Only  at  the  fifth  or 
sixth  gap,  i.  e.,  above  the  fork  of  the  stem,  is  there  a  continuity  established 
between  inner  and  outer  endodermis  and  between  medulla  and  cortex,  as 
in  the  adult  plant.  The  above  description  is  of  an  average  case.  The 
exact  position  of  each  stage  differs  according  to  the  size  of  the  individual 
sporeling.  The  whole  course  of  development  is  remarkably  identical  with 
that  described  by  Boodle  (1901)  for  the  early  stages  of  Aneimia  phyllitidis. 
Dennstczdtia  stops  at  the  solenostelic  stage,  while  Aneimia  goes  on  to 
become  dictyostelic. 

To  the  practiced  eye  the  first  leaf  of  a  young  fern  is  often  sufficient  to 
distinguish  the  species.  In  any  case  the  third,  fourth,  or  fifth  leaf  will 
bear  undoubted  specific  characteristics.  The  first  leaf  of  Dennst&dtia 
punctilobula  is  usually  two-parted,  with  each  part  bifid  at  the  apex  (figs. 
259,  267).  In  more  slender  examples  the  two  lobes  are  narrow,  elliptic, 
and  entire.  I  have  seen  two  cases  where  the  leaf  bore  but  one  elliptic 
entire  bit  of  lamina.  The  average  leaf  measures  0.32  cm.  to  0.38  cm. 
across.  Its  venation  is  simply  forked.  In  the  bud  it  is  folded  over  at  the 
tip  in  involute  manner,  but  could  hardly  be  called  circinate.  The  same  is 
true  of  the  rudiment  of  the  second  leaf.  The  second  leaf  is  also  broad 
and  lobed.  It  has  three  or  four  main  lobes,  each  bifid  or  emarginate  at 
apex.  It  is  larger  than  the  first,  being  0.46  to  0.81  cm.  in  width  and  0.4 
cm.  or  less  in  length  (figures  260,  261).  The  third  leaf  is  pinnately 


THE    YOUNG    SPOROPHYTE.  41 

divided,  with  a  comparatively  broad,  winged  rachis.  There  are  one  or 
two  pairs  of  pinnules  and  a  terminal  portion,  all  of  which  are  lobed  and 
crenated  (fig's.  262,  263).  The  fourth  and  succeeding-  leaves  are  pinnate 
like  the  third,  but  with  more  pinnae  (fig's.  264,  265).  All  of  these  early 
leaves  are  broadest  at  the  base  and  they  vary  from  deltoid  to  broadly 
lanceolate  in  shape.  But  in  outline  of  the  pinnae  and  pinnules  the  third 
and  fourth  leaves  are  exactly  like  the  mature  leaf.  They  are  thin  and 
fragile,  consisting-  only  of  upper  and  lower  epidermis  (fig's.  254,  266)  and 
one  layer  of  spongy  parenchyma  (fig-.  253).  Stomata  are  numerous  in 
the  lower  epidermis  of  each  leaf,  especially  on  the  pinnate  leaves.  A  few 
stomata  occur  scattered  over  the  backs  of  the  petioles  (fig-.  268).  The 
margin  of  the  leaf  is  strengthened  by  long:,  narrow,  indurated  cells  under- 
lying- the  epidermis  (fig".  251). 

The  first  two  leaves  are  devoid  of  hairs  of  any  kind.  Hairs  begin  to 
occur  on  the  third  leaf,  but  the  fourth  shows  three  kinds  of  trichome  struc- 
ture— glands,  moniliform  hairs,  and  acicular  hairs.  A  few  glands  (figf. 
258,  u)  occur,  thinly  scattered  on  the  upper  and  lower  surfaces  of  lamina 
and  rachis,  but  they  are  more  plentiful  on  the  petiole.  Each  one  consists 
of  one  to  three  larg-e,  swollen  cells.  They  probably  represent  the  glandular 
hairs  of  the  adult.  Moniliform  hairs  (figf.  258,  m)  consist  of  three  or  four 
cells,  each  of  which  is  broader  above  and  narrower  below.  They  lie 
appressed  to  the  leaf -surface.  They  are  plentiful  on  both  surfaces  of  the 
lamina  and  rachis,  but  there  are  none  at  all  on  the  petiole.  Acicular  hairs 
like  those  of  the  adult  leaf  are  plentiful  all  over  the  fifth  leaf,  and  on  the 
stem  apex.  They  are  four  to  seven  cells  long*  (commonly  4,  5,  or  6), 
thick- walled,  and  curve  outward  from  the  surface  of  both  the  lamina  and 
the  petiole. 

The  mature  petiole  of  the  early  leaves  is  slender,  flattened  above  and 
rounded  below  (fig".  248).  Under  an  uneven  epidermis  there  is  a  cortex 
composed  of  two  or  three  layers  of  larg-e,  thin- walled  cells.  In  this  are 
larg-e  intercellular  spaces.  A  well-defined  endodermis  demarcates  a  cyl- 
indrical vascular  bundle.  In  this  is  a  stout  transverse  band  of  xylem, 
surrounded  by  phloem  and  a  single  layer  of  pericycle.  The  xylem  con- 
sists of  narrow  spiral  and  scalariform  tracheids. 

As  stated  above,  the  first  leaf  is  derived  from  two  octants  of  the  embryo, 
not  from  one  alone,  and  gfrows  always  by  a  group  of  marginal  initials. 
These  undergo  sectioning-  and  halving-  as  in  the  adult  the  leaves  (fig-.  250). 
The  second  leaf  arises  from  the  stem-tip.  Its  development  has  not  been 
followed. 

I  have  not  determined  how  long-  it  takes  to  obtain  mature  plants  from 
spores.  Forked  stems  are  found  after  about  one  year.  In  some  cases 
certainly  another  season  intervenes  before  maturity  is  reached.  Probably 
they  never  fructify  before  the  third  or  fourth  summer. 


42  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 


DISCUSSION  OF  RESULTS. 

We  have  restricted  ourselves  thus  far  to  mere  description  of  the  develop- 
ment of  Dennst&dtia  punctilobula.  It  remains  to  point  out  in  order  some 
general  considerations  suggested  by  the  investigation. 

TAXONOMY. 

Whether  our  fern  belongs  in  the  Cyatheacese  or  the  Polypodiacese  should 
not  be  difficult  to  decide.  The  principal  differences  between  the  orders 
may  be  shown  by  a  table: 

CYATHEACESE.  POLYPODIACE^;. 

Annulus  a  complete  circle,  oblique.  Annulus  surrounding  three-fourths  of  spo- 

Antheridium  cover  multicellular.  rangium,  symmetrical. 

Cushion  of  prothallus  with  bristles.  Antheridium  cover  unicellular. 

Broad  cells  in  continuous  series  in  the  rhi-        Cushion  without  bristles. 

zogenous  line.  Rhizogenous  cells  separated  by  smaller 

cells. 

In  all  of  these  points  the  plant  now  under  discussion  agrees  with  the 
Polypodiaceae.  But  Bauke  (1876)  states  for  Dicksonia  rubiginosa  that 
its  antheridium  is  cyatheaceous.  Moore  (1857)  and  recent  writers  place 
D.  rubiginosa  Kaulf .  and  Dicksonia  punctilobula  Willd.  in  the  genus  Denn- 
sttzdtia.  Gwynne-Vaughan  (1903)  further  shows  that  D.  rubiginosa  has  a 
complicated  solenostelic  stem.  If  Moore  and  his  followers  are  correct, 
the  character  of  the  antheridium  must  cease  to  stand  as  a  distinction 
between  the  two  orders.  This  point  is  much  in  need  of  investigation 
in  other  Dicksonias  and  Dennstaedtias,  as  well  as  in  Davallia,  Lindsay  a, 
Microlepia,  and  the  allied  genera.  Cyatheaceous  root-structure  I  have 
observed  in  Cibotium  regale.  But  we  need  to  know  the  arrangement  of 
rhizogenous  cells  in  the  other  genera  just  named.  A  knowledge  of  these 
points  is  especially  needed  for  the  Melanesian  Z^wste^m  flaccida,  the  type 
of  the  genus.  For  it  may  yet  develop  that  our  North  American  fern  is 
not  referable  to  the  same  genus  with  D.  flaccida.  In  that  case  we  should 
have  to  adopt  the  generic  name  Sitobolium  Desv.  The  point  can  only  be 
settled  after  a  careful  examination  of  D.  flaccida  throughout  its  structure 
and  life-history.  The  removal  of  our  fern  from  the  genus  Dicksonia 
L'Herit.  is  generally  agreed  upon,  and  is  quite  sure  to  stand.  The  use  of 
the  name  Dicksonia  certainly  leads  to  confusion,  as  when  a  recent  European 
writer  speaks  of  our  plant  as  a  " tree-fern. ":  But  further  studies  along 
the  lines  indicated  are  needed  to  fully  establish  the  position.  Indeed,  it  is 
not  impossible  that  such  a  comparison  would  break  down  the  feeble  barrier 
between  Cyatheaceae  and  Polypodiaceae  by  showing  a  series  of  connecting 
links. 

*"Den  nordamerikanischen,  2-5'  hohen  Baumfarn."     Brick,  1897. 


DISCUSSION   OF   RESULTS.  43 

STELAR    MORPHOLOGY. 

Some  views  already  published  (1906)  on  this  point  may  be  repeated 
here.  The  development  of  the  seedling-  stem  supports  the  idea  of  Jeffrey 
and  Boodle  of  the  phylogfeny  of  the  fern-stem.  We  first  have  the  pro- 
tostele,  then  the  ectoploic  siphonostele,  and  finally  the  solenostele.  But 
there  is  no  evidence  of  any  influence  of  the  tissues  outside  the  vascular 
tube  upon  those  inside.  Each  interior  tissue  is  established  before  it  comes 
into  communication  with  its  external  homologfue. 

HOMOLOGY   OF   TISSUES. 

Indeed,  homology  of  tissues  can  not  be  determined  either  by  continuity 
or  by  origin  in  the  meristem.  We  may  not  homologize  the  medulla  of 
Dennst<zdtia  with  the  central  xylem  of  Lygodium  simply  because  both 
arise  from  the  inner  ends  of  the  segments  of  the  stem-initial.  Much  less 
could  we  identify  the  inner  endodermis  of  Dennst&dtia  with  any  of  the 
xylem  of  Lygodium.  On  the  other  hand,  the  continuous  endodermal 
layers  of  root,  stem,  and  leaf  in  Dennsttzdtia  must  be  considered  as  one 
homogeneous  tissue.  But  in  the  root-tip  the  endodermis  arises  just  out- 
side and  the  pericycle  just  inside  the  second  periclinal  wall  in  each  seg-- 
ment.  In  the  stem  the  endodermis  is  the  result  of  the  last  (second)  peri- 
clinal division  in  a  layer  of  plerome  which  also  gives  rise  to  the  pericycle. 
The  same  is  true  of  the  leaf — an  org-an  which  grows  at  first  by  a  three- 
sided  initial,  then  by  a  two-sided,  and  finally  by  a  group  of  marginal  cells. 
In  Dennstadtia  pundilobula,  therefore,  tissues  are  homologous  which  have 
the  same  structure  and  function,  in  spite  of  their  differences  of  origin 
(cf.  Goebel,  1900). 

The  same  conclusion  is  indicated  by  the  long--familiar  fact  that  in  roots 
of  dicotyledons  the  undoubtedly  homologous  primary  tissues  arise  from 
at  least  five  different  types  of  root -tip  (De  Bary,  1884,  p.  12).  Indeed, 
radically  different  types  of  tip  may  occur  in  allied  g-enera,  as  in  Nymphcea 
and  Nuphar.  And  it  is  not  impossible  that  different  types  may  be  found 
in  different  roots  of  the  same  individual  plant.  The  recent  discussion  of 
stem-tips  raises  the  same  point  in  questioning  the  validity  of  Hanstein's 
tissue  layers  (Schoute,  1903,  etc.).  It  seems  reasonably  certain  that  Han- 
stein's  layers  are  not  of  very  wide  application.  In  the  face  of  so  much 
evidence,  also,  Van  Tieg-hem's  denial  of  an  epidermis  to  the  roots  of  ferns, 
monocotyls,  and  Nymphaeaceae  becomes  quite  valueless.  These  plants 
have  just  as  real  an  epidermis  as  have  others. 

INDEPENDENCE    OF    MERISTEM    AND    MATURE   TISSUES. 

The  fact  is  that  the  development  and  structure  of  the  mature  tissues 
are  to  a  large  extent  independent  of  the  development  and  structure  of 
the  meristem  from  which  they  are  derived.  The  lowest  plant  with  cell- 
division  in  three  planes  is  essentially  meristematic.  From  such  a  beg-in- 


44  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

ning  meristems  have  had  a  regular  and  orderly  phylogenetic  history  {cf. 
Bower,  1889).  From  the  meristem  a  more  or  less  homogeneous  paren- 
chyma is  directly  derived.  Very  soon,  however,  farther  differentiation 
occurs  in  the  older  parenchyma — the  parts  farthest  removed  from  apical 
meristem.  This  differentiation  has  also  been  modified  in  course  of  time 
in  response  to  the  environment  and  the  needs  of  the  plant.  But  there  is 
no  reason  to  suppose  that  the  changes  in  the  meristem  should  have  any 
direct  relation  to  those  in  the  older  portions.  Meristem  develops  from  a 
growing  point  and  its  structure  is  influenced  largely  by  the  shape,  size, 
number,  and  position  of  the  initial  cells.  Mature  tissues  develop  from 
below  upward,  and  are  shaped  out  of  meristem  in  response  to  stimuli 
which  come  chiefly  from  the  more  mature  cells.  While  this  independence 
of  meristem  and  mature  tissues  seems  plainly  indicated  by  a  comparison 
of  plants  as  they  commonly  occur,  it  is  also  capable  of  experimental  inves- 
tigation. Some  of  the  most  promising  material  for  this  purpose  would  be 
in  the  genera  Gleichenia  {cf.  Boodle,  1901)  and  Lindsay  a  {cf.  Tansley  and 
Lulham,  1902).  But  this  is  a  subject  which  has  yet  to  be  followed  out. 


Synony7ny  of  generic  names •,  and  list  of  type  species  on  strict  Linncean  priority. 

1.  Polypodium — Linnaeus,  1753 — Type:  P.  lanceolatum  (first  species  named.) 

2.  Dicksonia— L'Heritier,  1788— Type:  D.  culcita  (or  D  arbor escens}. 

3.  Aspidium — Swartz,  1800— Type:    A.  articulatum  (fide  Underwood,  1899). 

4.  Dennstcedtia — Bernhardi,  1800— Type:  D.flaccida=Trichomenesflaccidum  Forst. 

5.  Nephrodium — Michaux — Date  and  type  uncertain.    Cf.  Underwood,  1899,  p.  265.* 

6.  Sitobolium — Desvaux,  1827 — Type:  S.  punctilobum. 

7.  Sitolobinm — J.  Smith,  1841 — Type:  S.  punctilobum. 

8.  Litolobium — G.  Kunze,  1848 — Type:  L.  punctilobum. 

9.  Adectum — Link,  1841 — Type:   A.pilosiusculum. 

*Cf.  Davenport  in  Rhodora,  4:is8  ff.,  Aug.  1902. 


vSYNONYMY.  45 

SYNONYMY. 

Nephr  odium  punctilobulum  Michaux,  1803,2:268. 
A  spidium  punctilobulum  Swartz,  1806,  p.  60. 

punctilobum  Willdenow,  1810,  5:279. 

Pursh,  1814,2:664. 

Polypodium  pilosiusculum  Muhlenberg,  in  Willd.,  1809,  p.  1076. 
Willdenow,  in  Schkuhr,  1809,  p.  125. 

Dicksonia  pilosiuscula  Willdenow,  1809,  p.  1076;  1810,  5:  484. 
Poiret,  1811,  2:472. 
Pursh,  1814,  2:671. 
Nuttall,  1818,  2:253. 
not  Raddi,  1825,  p.  63. 
Sprengel,  1827,  4:  122. 
Darlington,  1837,  p.  584;  also  ed.  n. 
Hooker,  1840,  2:  264. 

Bigelow,  1814,  p.  254;  1824,  p.  397;  1840,  p.  424. 
Eaton,  1836,  p.  277. 
Eaton  and  Wright,  1840,  p.  224. 
Torrey,  1843,  2:  502. 
Wood,  1846,  p.  633;  1864,  p.  820. 
Macoun  and  Burgess,  1884,  p.  222. 
Gray,  1889,  p.  691,  pi.  18. 
Macoun,  1890,  p.  285. 
Wilson,  1897,  p.  8. 
Parsons,  1899,  pp.  114-119. 
Clute,  1901,  p.  230. 
Waters,  1903,  pp.  64,  68,  286-290. 
Eastman,  1904,  p.  64. 
Dicksonia pubescens  Schkuhr,  1809,  p.  125,  pi.  131. 

Presl,  1836,  p.  136. 

Sitobolium  punctilobum  Desvaux,  1827,  p.  262-263. 
Sitolobium  punctilobum  J.  Smith,  1846  a\  1846  ^,  p.  70. 

pilosiusculum  J.  Smith,  1841,  p.  418;  1842,  p.  434. 
Adectum  pUosiiisculum  Link,  1841,  p.  42. 
Dicksonia  punctiloba  Hooker,  1846,  1:  79. 
Fe'e,  1850,  p.  335. 
Lowe,  1867,  8:  123-124,  pi.  42. 
Hooker  and  Baker,  1868,  p.  54;  1874. 
Gwynne-Vaughan,  1901,  p.  85;  1903,  pp.  691,  730. 
Litolobium  [punctilobulum']  Kunze,  1848  (1846),  p.  88. 
Dicksonia  punctilobula  Gray,  1848,  p.  628;  1856;  1858,  p.  595;  1859,  p.  595;  1867,  p.  669,  pi. 

11;  1880,  p.  669. 

Kunze,  1848,  p.  88  (written  in  1846);  1850  b,  p.  249. 
Darlington,  1853,  p.  394. 
Mettenius,  1856,  p.  105. 
Provancher,  1862,  p.  720. 
Ball,  1876,  p.  155. 
Williamson,  1878,  p.  119,  pi.  45- 
Eaton,  1879,  1:  339-344^  pi.  44- 
Fowler,y?</<?  Macoun  and  Burgess. 
Underwood,  1888;  1893. 
Britton  and  Brown,  1896,  1:  12. 
Chapman,  1860,  p.  597;  1883,  p.  597;  1897,  p.  635. 
Dennstccdtia  punctilobula  Moore,  1857,  pp.  97,  307. 

Lawson,  1864,  p.  287;  1888,  p.  233. 
DeBary,  1884,  p.  284. 
Underwood,  1900  a,  1:  472:  1900  c,  p.  122. 
Britton,  1901,  p.  19. 
Small,  1903,  p.  18. 
Keller  and  Brown,  1905,  p.  14. 
Dennstcedti a  Punctiloba  Hooker  and  Baker. 
Christ,  1897,  p.  312. 
Diels,  1899,  p.  217. 


46 


STRUCTURE   AND    LIFE-HISTORY    OF    HAY-SCENTED    FERN. 


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48  STRUCTURE   AND    LIFE-HISTORY   OF    HAY-SCENTED    FERN. 

BIBLIOGRAPHY. 

ATKINSON,  G.  F.     1894.    The  Study  of  the  Biology  of  Ferns. 

BALL,  E.  H.     1876.     The  Indigenous  Ferns  of  Nova  Scotia,  in  Proc.  and  Trans.  Nov. 

Scot.  Inst.  of  Nat.  Sci.,  4:  155. 
BAUKE,  H.     1876.    Entwicklungsgeschichte  des  Prothalliums  bei  den  Cyatheaceen,  ver- 

glichen  mit  derselben  bei  den  anderen  Farrnkrautern,  in  Jahrb.  f.  wiss.  Botanik, 

10:  49-116,  pis.  6-10. 
BERNHARDI,  D.  I.  I.    1800.    Tentamen  alterum  filicesin  genera  redigendi,  in  Schrader's 

Journal  fiir  die  Botanik.  Gottingen,  vol.  2,  parts  i  and  2,  pp.  121-136. 
BIGELOW,  J.  1814-1840.  Florula  Bostoniensis,  ed.  i,  1814;  n,  1824;  in,  1840. 
BOODLE,  L.  A.  1901.  Comparative  Anatomy  of  Hymenophyllaceas,  Schizaeaceae,  and 

Gleicheniaceas.    II.  On  the  anatomy  of  the  Schizaeaceae.    In  Annals  of  Botany, 

15:359-423.    June. 
BOWER,  F.  O.     1889.    The  Comparative  Examination  of  the  Meristems  of  Ferns  as  a 

Phylogenetic  Study,  in  Annals  of  Botany,  3:  305-393 

BRICK,  C.     1897.     Review  of  Wilson,  1897,  in  Botan.  Jahrsber.  1897,  1:  470. 
BRITTON,  N.  L.     1901.     Manual  of  the  Flora  of  the  Northern  States  and  Canada,  p.  19. 

-  and  BROWN,  AD.     1896.    An  Illustrated  Flora  of  the  Northern  United  States,  Can- 

ada, and  the  British  Possessions,  1:  12. 
CAMPBELL,  D.  H.     1887.     The  Development  of  the  Ostrich  Fern,  in  Mem.  Boston  Soc. 

Nat.  Hist.,  4:  17-52,  pis.  4-7. 
1895;  1905.    The  Structure  and  Development  of  the  Mosses  and  Ferns.    Macmillan, 

New  York:  ist  and  2d  ed. 
CHAPMAN,  A.  W.  1860-1897.     Flora  of  the  Southern  United  States;   ed.  i,  1860;  n,  1883; 

in,  1897. 

CHRIST,  H.     1897.     Die  Farnkrauter  der  Erde,  Jena. 
CHRYSLER,  M.  A.     1904.     The  Development  of  the  Central  Cylinder  of  Araceae  and 

Liliaceae,  in  Botanical  Gazette,  38:  161-184,  pis.  xn-xv.    Sept.  23,  1904. 
CLUTE,  W.  N.     1901.     Our  Ferns  in  their  Haunts.     New  York;  332  pp. 
CONARD,  H.  S.     1906.     Morphology  of  Fern  Stem,  in  Johns  Hopkins  Circulars,  pp.  95- 

98.     May. 
COPELAND,  E.  B.    1902.    The  Mechanism  of  Stomata,  in  Ann.  of  Bot..  1 6:  327-364,  pi.  13. 

June. 

DARLINGTON,  WM.     1853.    Flora  Cestrica;  ed.  i,  18375111,  1853.    Philadelphia. 
DAVENPORT,  G.  E.     Dicksonia  pilosiuscula  var.  cristata,  in  Rhodora,  2:  220-226.     Not 

seen. 

-  1905.     Reversions  and  their  Fluctuations,  in  Fern  Bulletin,  13:  106-107. 

DE  BARY,  A.    1877;  1884.     Comparative  Anatomy  of  Phanerogams  and  Ferns.     German 

ed.,  1877;  English  trans.,  1884. 
DESVAUX,  N.  A.     1827.     Prodrome  de  la    Famille  des  Fougeres,  in  Mdm.  Soc.  Linn. 

Paris,  6:  171-337.     See  pp.  262-263. 
DIELS,  L.     1899.     Polypodiaceae  in  Engler  and  Prantl's  Natiirlichen  Pflanzenfamilien, 

1-4:  217-218.     Sept.  12,  1899. 

EASTMAN,  H.    1904.     New  England  Ferns  and  their  Common  Allies.    Boston.    161  pp. 
EATON,  A.     1836.     Manual  of  Botany  for  North  America.    Albany. 

—  and  WRIGHT,  J.     1840.     North  American  Botany;  ed.  vm. 
EATON,  D.  C.    1879.   The  Ferns  of  North  America.   2  vols.,  1879-1880,  81  plates.   Salem, 

Mass. 
FEE,  A.  L.  A.   1850.    Genera  Filicum  (Cinquieme  Memoire  sur  la  Famille  des  Fougeres). 

Exposition  des  Genres  de  la  Famille  des  Polypodiace'es.    Paris  and  Strasbourg. 
FORD,  S.  O.     1902.     The  Anatomy  of  Ceratopteris  thalictroides,  in  Annals  of  Botany, 

16:  95-122,  pi.  6.     March. 
FOWLER.     New  Brunswick  Catalogue. 
GILBERT,  B.  D      1905.     Observations  on  North  American  Pteridophytes,  n,  in    Fern 

Bulletin,  13:  100-104. 
GRAY,  ASA.     1848-1889.     Manual  of  the  Botany  of  the  Northern  United  States;  ed.  i, 

1848;  11,  1856;  in,  1858;  iv,  1859;  v,  1880;  vi,  1889. 

GOEBEL,  K.     1887.     Outlines  of  Classification  and  Special  Morphology,  English  trans- 
lation. 

—  1900.    Organography  of  Plants.    Transl.  by  Balfotir,  1:  14-17- 
GWYNNE-VAUGHAN,  D.  T.    1901.    Observations  on  the  Anatomy  of  Solenostelic  Ferns 

I.  Loxosoma.     In  Annals  of  Botany,    15:  71-99. 

1903.     Ditto,  n,  1.  c.,  17:  689-743. 

HABERLANDT,  G.  1904.     Physiologische  Pflanzenanatomie,  ed.  3. 


BIBLIOGRAPHY.  49 

HOOKER,  W.  J.     1840.     Flora  boreali-americana,  2:  264.     London. 

-  1846.    Species  Filicum,  vol.  i. 

—  and  BAKER,  J.  G.     1874.     Synopsis  Filicum,  ed.  i,  1868;  n,  1874. 

JANSE,  J.  M.     1895.     Les  endophytes  radicaux  de  quelques  plantes  Javanaises,  in  Ann. 

du  Jardin  Botanique  de  Buitenzorg,  14:  53-201,  pi.  v-xv.     (Vol.  14  is  dated 

1897.) 
JEFFREY,  E.  C.     1897.    The  Morphology  of  the  Central  Cylinder  in  Vascular  Plants,  in 

Report  of  the  British  Assoc.  for  the  Adv.  of  Sci.  1897,  pp.  869-870. 
JOHNSON,  D.  S.    1898.    On  the  development  of  the  leaf  and  sporocarp  in  Marsilia 

quadrifolia  L.,  in  Annals  of  Botany,  12:  119-147.    June. 
KELLER,  I.,  and  BROWN,  S.    1905.    Handbook  of  the  Flora  of  Philadelphia  and  Vicinity. 

Phila.  Bot.  Club. 
KNY.     1875.      Die  Entwickelung  der  Parkeriaceen   dargestellt  an  Ceratopteris  thal- 

ictroides  Brongn.,  in  Nova  Acta  d.  Leopoldinisch  Carolinische  Akademie  der 

Naturforscher,  37:  1-80,  pi.  18-25. 
KUNZE,  G.     1848.     In  Silliman's  American  Journal  of  Science  and  Arts,  2d  series,  6: 

80-89.    "Notes  on  some  ferns  of  the  United  States,"  written  1846. 

-  1850^.     Einige  Bemerkungen  iiber  Dicksonia,  in  Botan.  Zeitung,  8:  57-62. 

-  1850^.     Index  Filicum  (sensu  latissimo),  in  Linnaea,  23:  209-323. 

LACHMANN,  P.  1877.  Structure  et  croissance  de  la  racine  des  Fougeres,  in  Bull.  Soc. 
bot.  Lyon.  Not  seen. 

—  1885.     Recherches  sur  la  morphologic  et   1'anatomie  des  Fougeres,  in  Comptes 

Rendus,  101:  603.    Not  seen. 

-  1887.     Structure  et  croissance  de  la  racine  des  Fougeres,  et  1'origine  des  radicelles. 

Bull.  Soc.  bot.  de  Lyon. 

LAWSON,  Geo.  1864.  Synopsis  of  Canadian  Ferns  and  Filicoid  Plants,  in  Trans.  Bot. 
Soc.  Edinb.,  8:  20-50.  vidi.  Also  in  Edinb.  New  Philos.  Journ.,  N.  S.,  19:io2- 
116,273-291,  1864;  Canad.  Naturalist,  N.  S.,  1:  262-380,  1864.  Not  seen. 

-  1888.     The  Fern  Flora  of  Canada.    A.  W.  Mackinlay,  Halifax.     Not  seen. 
L'HERITIER  DE  BRUTELLE,  C.  L.     1788.     Sertum  Anglicum.     Folio,  36  pp.,  34  plates. 

Not  seen. 
LINK,  H.  F.     1841.     Filicum  species  in  horto  regio  botanico  Berolinensi  cultae.    179  pp. 

Not  seen. 

LINNAEUS,  C.     1753.    Species  Plantarum. 

LOWE,  E.  J.     1867.    Ferns:  British  and  Exotic,  vol.8.     London. 
MACOUN,  J.     1890.     Catalogue  of  Canadian  Plants.    Part  v,  Acrogens.    Geological  and 

Natural  History  Survey  of  Canada,  vol.  2.    Montreal. 

—  and  BURGESS,  F.  W.      1884.     Canadian  Filicineae,  in  Trans.  Roy.  Soc.  Canada, 

2:  163-227;  sec.  4. 

MAXON,  W.  R.     1899.     A  variety  of  Dicksonia,  in  Fern  Bulletin  7":  63-64.     Not  seen. 
METTENIUS,  G.  H.     1856.     Filices  horti  botanici  Lipsiensis. 
MICHAUX,  A.     Hort.  med.  Paris.  Cat.  not  seen. 

—  1803.     Flora  Boreali-Americana,  2:  268. 
MOORE,  THOS.     1857.     Index  Filicum. 

NAGELI,  C.,  and  LEITGEB,  H.     1865.     In  Sitzber.  baier.  Akad.  Wiss. 

—  1868.    Entstehung  und  Wachsthum  der  Wurzeln  in  Beitr.  z.  wiss.  Botanik,  Hft.  iv, 

pp.  74-160,  pis.  xi-xxi. 

NEWMAN,  E.     1841-1851.    The  Phytologist,  5:  236,  fide  Moore,  1857. 
NUTTALL,  THOS.     1818.     The  Genera  of  North  American  Plants,  and  a  catalogue  of 

the  species  to  the  year  1817.     Philadelphia. 
PARSONS,  F.  T.     1899.     How  to  Know  the  Ferns.     New  York. 
POIRET,  J.  L.  M.     1811,    Article  "Dicksonia,"  in  Lamarck,  Encyclopedic  Methodique 

Botanique.     Supplement,  tome  II,  p.  472.     Paris,  1811. 
PRANTL,  K.     18750.     Hymenophyllaceen.     Leipzig. 

1875^.    Verzweigung  des  Stammes,  in  Flora,  No.  34.     Not  seen. 

PRESL,  K.  B.     1836.    Tentamen  pteridpgraphiae,  seu  genera  filicarum  praesertim  juxta 

venarum  decursum  et  distributionem  exposita.     Prag. 
PROVANCHER,  L.     1862.     Flore  Canadienne.     Quebec.    842  pp.    Not  seen. 
PURSH,  F.     1814.     Plants  of  North  America,  2:  664. 
RADDI,  J.     1825.    Plantarum   Braziliensium    nova  genera  et  species  novas  vel  minus 

cognitaa.     Florentiae. 
Russow,  EDM.   1871.  VergleichendeUntersuchungen  iiber  die  Leitbundelkryptogamen. 

in  M6m.  de  1'Acad.  Imp.  de  St.  Pe'tersbourg,  ser.  vn,  19:  80. 
SACHS,  J.     1875.     Text-book  of  Botany.    English  transl. 


50  STRUCTURE   AND    LIFE-HISTORY   OF   HAY-SCENTED    FERN. 

SADEBECK,  R.     1873.     In  Verb.  Hot.  Ver.  Prov.  Brandenburg,  15. 
1874.     Farnblatt. 

—  1878.     Vascular  Cryptogams  in  Schenck's  Handbuch. 

—  1898.     Pteridophyta  in  Engler  and  Prantl's  Natiirlichen  Pflanzenfamilien,  1-4  A. 
SCHKUHR,  C.      1809.      Vier  und  zwanzigste  Klasse  des  Linnd'schen  Pflanzensystems, 

oder  Kryptogamische  Gewachse. 
SCHOUTE,  J.  C.     1903.     Die  Stelar-theorie.     Jena. 

SMALL,  J.  K.     1903.     Flora  of  the  Southeastern  United  States.     New  York. 
SMITH,  J.     1841.     Enumeratio  Filicum  Philippinarum,  in  Hooker's  Journ.  of  Botany,  3: 

392-422. 
1842.     An  Arrangement  and  Definition  of  the  Genera  of  Ferns,  with  observations 

on  the  affinities  of  each  genus,  in  Hooker's  London  Journ.  of  Botany,  1:  419-438. 

-  18460,  in  Bot.  Mag.  Comp.,  36.     Not  seen. 

1846^.     Catalogue  of  the  Ferns  grown  at  Kew.     Not  seen. 

SPRENGEL,  K.     1827.     Caroli  Linnaei  Systema  vegetabiliurn,  vol.  4.     Not  seen. 
STRASBURGER,  E.     1897.     Das  Botanische  Practicum,  ed.  3. 
STRASBURGER,  NOLL,  etc.     1898.     Text  Book  of  Botany,  English  translation. 
SWARTZ,  O.     1800.     Genera  et  Species  Filicum,  in  Schrader's  Journ.  fiir  die  Botanik, 
2:  1-120. 

-  1806.     Synopsis  Filicum. 

TANSLEY,  A.  G.,  and  LULHAM,  R.  B.  J.  1902.  On  a  new  type  of  Fern-stele,  and  its 
probable  phylogenetic  relations,  in  Annals  of  Botany,  16:  157-164.  March. 

THOMAE,  K.     1886.     Blattstiele  der  Fame,  in  Jahrb.  f.  wiss.  Bot.,  1<T:  129. 

TORRBY,  J.     1843.     A  Flora  of  the  State  of  New  York.     Albany.     2:  502. 

UNDERWOOD,  L.  M.  1888;  1893;  1900^:.  Our  Native  Ferns  and  their  Allies.  Ed.  i, 
1888;  vi,  1900. 

—  1899.    A  Review  of  the  Genera  of  Ferns  proposed  prior  to  1832,  in  Mem.  Torr.  Bot. 

Club,  6:  No.  4. 

—  1900^.    Article  "Dennstaedtia"  in  Bailey,  Cyclopedia  of  American  Horticulture,  1: 

472. 

1900^.    Article  "Dicksonia,"  1.  c.,  p.  480. 

VAN  TIEGHEM,  PH.,  and  DOULIOT,  H.     1888.      Recherches  comparatives  sur  1'origine 

des  membres  endogenes  dans  les  plantes  vasculaires,  in  Ann.  Sci.  Nat.  Bot., 

ser.  7,  8:  127-132,  435-438. 
VINES,  S.  H.     1894.    Text  Rook  of  Botany. 
WATERS,  C.  E.     1903.     Ferns.     A  manual  for  the  northeastern  States,  with  analytical 

keys  based  on  the  stalks  and  on  the  fructification.     Holt,  New  York.     1903. 

Cf.  pp.  286-290. 
WlLLDENOW,  C.  L.      1809.     Enumeratio  plantarum   horti  regii  botanici  Berolinensis. 

Berlin. 

1810.     Species  plantarum.     Ed.  iv. 

WILLIAMSON,  J.     1878.     Ferns  of  Kentucky.     Louisville. 

WILSON,  F.     1897.    "Dicksonia  pilosiuscula,"  in  Asa  Gray  Bulletin,  5:  7-9.     Not  seen. 
WOOD,  A.     1846.     Manual  of  Botany;  editions  of  1846  and  1864. 


LIST   OF   ILLUSTRATIONS   AND   EXPLANATION    OF   PLATES.  51 

EXPLANATION  OF  PLATES.* 

Key  to  index-letters  on  figures  (except  figs.  47-51). 

a,  initial  cell.  ip,  inner  pericycle.  r   root 

c,  cortex.  iph,  inner  phloem.  rfi   root-hair 

cy,  conjunctive  parenchyma.  is,  inner  sclerenchyrna.  rf  rootlet 

e,  epidermis.  ist,  inner  starchy  tissue.  *,  sclerenchvma 

/,  fundamental  tissue.  Wf  endodermis.  sa    air-space 

A,  hypodermis.  p,  pericycle.  gp   spiral  tracheid. 

i,  rhizogenous  cell.  pa,  parenchyma.  «<,  starchy  tissue. 

ic,  inner  fundamental  tissue.  ph,  phloem.  I  tracheid 

icj,  inner  conjunctive  paren-  p(,  plerome.  v,  sieve-tube. 

chyma.  pph,  protophloem.  x   xylem 

in,  inner  endodermis.  px,  protoxylem. 

Letters  used  variously:  b,  d,  m,  o,  u,  tr,  1,  2,  3,  etc. 

PLATE  r. 

1.  Habitat  of  D.  punctilobula;  Massachusetts.     Photo  by  C.  E.  Waters,  Ph.D. 

2.  Leaves  as  they  grow.  From  Waters,  1903,  by  courtesy  of  the  author  and  publishers 

PLATE  2: 

3.  Rhizome,  natural  size,  showing  fork,  leaf  bases,  and  leaf-shoots. 

4.  Leaf-bud  with  two  unequal  leaf-shoots,  natural  size.     3  and  4  from  photo  by 

C.  E.  Waters,  Ph.D. 

5.  Portion  of  pinna  showing  pinnules,  lobes,  crenations,  sori,  and  hairs.     X  about 

10.     From  Waters,  1903,  by  courtesy  of  the  author  and  publishers. 
PLATE  3: 

6-8.  Diagrams  showing  distances  between  rootlets,  natural  size. 

9.  Diagrammatic  projection  of   a  piece  of  stem  5  cm.  long,  including  apex,  with 

figures  to  indicate  the  number  of  roots  attached  to  each  eighth  of  the 

circumference. 

10-13.  Diagrams  of  divisions  of  ro^t-cap  segment  as  seen  from  distal  side. 
14.  Diagrammatic  longitudinal  section  of  root-tip,  showing  the  origin  of  the  various 

tissues.     Walls  numbered  in  order  of  formation. 
15-22.  Diagrams  of  division  in  segments  of  root  initial.     Walls  numbered  in  order 

of  formation. 
PLATE  4: 

20-22.  See  above. 

23.  Root-tip  in  longitudinal  section.     X  210. 

24.  Longitudinal  section  of  an  anomalous  root-cap,  showing  two  layers  from  one 

segment  at  point  marked  *.     X  210. 
25-32.  Successive   transverse  sections  of  a  root-tip.    25,  26  in  cap;  27-32  in  root;  b 

indicates  root-cap.     Initial  and  second  set  of  segments  dotted.     All  in 

the  same  relative  position.     X  210. 
PLATE  5: 

28-32.  See  above. 

33.  Transverse  section  of  same  root,  o.i  mm.  farther  up  than  32;  b,  root-cap.    X  210. 

34.  Rhizogenous  cell,  undivided,  in  transverse  section  of  root.     X  210. 

35.  Rhizogenous  cell,  second  division,  in  similar  section.     X  210. 

PLATE  6: 

36.  Rhizogenous  cell,  third  division.     X  210. 

37.  First  division  in  rhizogenous  cell;  longitudinal  radial  section  of  root.     X  210. 

38.  Endodermis    with   rhizogenous   cells,   tangential   view.      Reconstruction   from 

serial  longitudinal  sections  of  root.     X  210. 

39.  Ditto:  another  root.     X  210. 

40.  Oblique  tangential  view  of  rhizogenous  cell,  showing  its  first  three  divisions. 

X    210. 

41.  Rootlet  initial  from  longitudinal  tangential  section  of  root.     X  210. 

42.  Rootlet  initial  in  transverse  section  of  root;  one  cap-layer.     Cells  within   the 

chain  of  arrows  have  arisen  by  proliferation  of  cortex.     X  210. 

43.  Ditto;  two  cap-layers,  £,  and  digestive  layer  of  cortex,  o.     X  210. 

44.  Part  of  transverse  section  of  nearly  mature  root.     X  210. 

45.  Transverse  section  of  stele  of  fully  mature  root.     X  210. 

46.  Part  of  transverse  section  of  old  root  with  outer  layers  shedding  off.     X  100. 

*A11  figures  are  of  Qennvoetdtia  punQtUobula  unless  otherwise  stated  in  the  description. 


52  STRUCTURE   AND    LIFE-HISTORY   OF   HAY-SCENTED    FERN. 

PLATE  7: 

47.  Root-tip  of  Aspidium  marginale^  longitudinal  section;  #,  first  periclinal  wall; 

6,  second  .periclinal;  <?,  endodermis.     X  210. 

48.  Root-tip  of  Aspidium  molle,  longitudinal  section;  e,  endodermis.     X  210. 

49.  Root-tip  of  Didymochlccna  lunulata,  longitudinal  section;  e,  endodermis.  X  210. 

50.  Root-tip  of  Ceratopteris  thalictroides,  longitudinal  section.     X  210. 

51.  Root-tip  of  Onoclea  sensibilis,   longitudinal  section;  £,  endodermis.     X2io. 

52.  Cortex  of  root  of  Dennscetdtia  punctilobula,  showing  mycorhiza,  <?;  transverse 

section  of  root.     X  210. 

53.  Ditto.     Longitudinal  section.     Entrance  of  fungus  through  a  root-hair.     X  210. 

54.  Rootlet,  transverse  section.     Pericycle  dotted ;  sextant  walls  heavy.     X  210. 

55.  Junction  of  pericycle  of  root  and  rootlet.     X  210. 

56.  Junction  of  xylem  of   root  and  rootlet;    longitudinal  radial   section   of  root. 

X  200. 

57.  Ditto;  tangential  to  rootlet.     X  200. 

PLATE  8: 

58.  Two  tracheids  from  the  junction  of  the  vascular  bundles  of  root  and  stem. 

Macerated  and  teased  out.     X  210. 

59.  Young  root  in  longitudinal  section  of  stem  apex.     From  point  marked  3  in  fig. 

70.       X    210. 

60.  Longitudinal  section  of  older  root,  about  to  pass  out  from  stem;   b,  root-cap. 

From  point  marked  4  in  fi<?.  70.     X  210. 

61.  Junction  of  root  shown  in  fig.  60  with  stem  bundle.     X  210. 

62.  Sharply  bent  tracheid  at  junction  of  root  and  stem,  from  same  section  as  fig.  99. 

X  210. 
PLATE  9: 

63.  Part  of  transverse  section  of  stem.     Area  included   in  dotted  lines   at  2   in 

fig-  97-  . 

64.  Part  of  longitudinal  section  of  stem.    Area  included  in  dotted  line  n  in  fig.  70. 

65.  Ends  of  sieve-tubes  of  stem;  macerated  and  teased. 

66.  Diagram  of  node;  longitudinal  section  of  stem  and  leaf-base;  If,  vascular  bundle. 

PLATE  10: 

67.  Rhizome,  transverse  section.     Photomicrograph. 

68.  Vascular  bundle  of  petiole,  transverse  section.     Photomicrograph. 

69.  Rachis  of  leaf,  transverse  section.     Photomicrograph. 

PLATE  n: 

70.  Diagram  of  stem  apex,  longitudinal  section,     i,  9,  dotted  outlines  of  leaf  rudi- 

ments, showing  their  position  relative  to  the  stem  apex.  2,  3,  4,  7,  8, 
location  of  root-tips  of  various  ages  (cf.  figs.  59,  60).  5,  beginning  of 
protophloem.  6,  point  where  endodermis  and  pericycle  are  separated. 
10,  beginning  of  lignification  in  xylem.  u,  area  drawn  in  fig.  64. 

71.  Stem-initial  in  transverse  section.     X  210. 

72-75.  Segmentation  and  sectioning  in  the  apex  shown  in  fig.  71.  Segments  num- 
bered in  order  of  age. 

76.  Isolated  cells  of  sclerotic  medulla;  macerated  and  teased. 

77.  Ditto. 

78.  End  of  scalariform  tracheid  of  stem;  macerated  and  teased. 

79.  Ditto. 

80.  Isolated  cells  of  sclerotic  cortex  of  stem;  macerated  and  teased. 

81.  Isolated  cells  of  conjunctive  parenchyma  of  stem;  macerated  and  teased. 

82.  Vascular  bundle  of  stem  and  leaf,  with  leaf-shoot  dissected  out  and  viewed  from 

the  side;  o,  leaf-gap;  m,  leaf-shoot;  tr,  leaf-trace;  u,  anterior  end  of  por- 
tion of  vascular  bundle  of  stem.     Drawn  from  nature  by  Miss  M.  E. 
Rogers. 
PLATE  12: 

83-87.  Diagrams  of  successive  cross-sections  of  a  fork  of  a  stem,  with  ventral  leaf. 
Dotted  line  indicates  boundary  between  sclerotic  and  starchy  tissues; 
vascular  bundle  section-lined;  /r,  leaf-trace. 

88-92.  Diagrams  of  successive  cross-sections  of  rachis,  showing  departure  of  rib  of 
pinna.  Dotted  line  bounds  sclerenchyma;  solid  line  is  endodermis; 
xylem  is  section-lined;  £,  trace  of  pinna.  Fig.  88  is  lowermost,  92  upper- 
most. 


LIST    OF    ILLUSTRATIONS    AND  EXPLANATION    OF    PLATES.  53 

PLATE  i%,  continued: 

93-96.  Diagrams  of  successive  cross-sections  of  petiolar  bundle  giving  off  a  leaf- 
shoot  bundle.     Conventional  signs  as  in  figs.  83-87;  /«,  leaf-shoot. 

97.  Diagrammatic  cross-section  of  leaf-shoot,  near  its  origin.    Conventional  signs  as 

m  figs.  88-92;  2  indicates  part  drawn  in  fig.  63 

98.  Isolated  tracheids  of  fork  of  stem. 

99.  Diagram  of  fork  of  stem,  longitudinal  section.     Conventional  signs  as  in  figs. 

83-87. 

100.  Diagrammatic  cross-section  of  node;  stem  to  right.     Conventional  signs  as  in 

figs.  83-87. 

101.  Diagrammatic  transverse  section  of  base  of  petiole.     Conventional  signs  as  in 

figs.  88-93;  a,  region  of  stomata. 

102.  Diagram  of  junction  of  root  and   stem,   longitudinal    section.      Cortex  and 

medulla  section-lined. 
PLATE  13: 

103.  Stem-initial  with  four  segments,  in  transverse  section,  with  leaf-rudiment,  d,  at 

left.     X  210. 

104.  Transverse  section  of  stoma.     After  Copeland,  1902. 

105.  Glandular  hair  of  leaf,  with  two  gland-cells.     X  210. 

106.  Longitudinal  section  of  stem   apex;  heavy  lines  at  right  show  boundary  of 

vascular  bundle;    d,   intercalary   growth   of   hair;    u,  origin  of   hair. 
Composite.     X  210. 

107.  Protophloem  in  transverse  section  of  stem  near  apex.     X  210. 

108.  Transverse  section  of  stem-bundle  at  margin  of  leaf-gap,  showing  continuity  of 

inner  and  outer  vascular  tissues.     X  210. 

109.  Oblique  transverse  section  of  stem-initial,  with  leaf-rudiment  (b)   in   fourth 

segment.     X  360. 
no.  Protophloem  and  earliest  lignified  xylem  in  transverse  section  of  stem  near 

apex.     See  lettering  on  fig.  107. 
PLATE  14: 

in.  Lower  epidermis  of  leaf.     X  210. 

112.  Upper  epidermis  of  leaf.     X  210. 

113.  Transverse  section  of  leaf ;  chloroplasts  diagrammatic.     X  210. 

114.  Diagrammatic  transverse  section  of  rachis  near  summit;   xylem  shaded;   ;//, 

parenchymatous  region  connecting  with  stomata;  tr,  trace  of  pinna. 

115.  Inner  surface  of  indusium,  near  margin.     X  210. 

116.  Cavity  parenchyma  (d)  in  transverse  section  of  rachis.     X  210. 

117.  Ditto,  in  longitudinal  section.     X  210. 

118.  Early  stage  of  leaf-initial  in  transverse  section  of  stem  apex. 

119.  Outer  surface  of  indusium.     X  210. 

120.  Inner  surface  of  indusium,  near  base,  with  stomata.     X  210. 

121.  Formation  of  leaf-initial  in  stem  apex;  later  stage  than  fig.  118.    Transverse 

section. 
PLATE  15: 

122-127.  Serial  transverse  sections  of  leaf-rudiment,  showing  transition  from  four- 
sided  to  two-sided  initial;  122  is  through  apex  of  rudiment,  127  through 
its  base. 

128,  129.  Longitudinal  sections  of  stem  apex  with  leaf-rudiment,  taken  0.025  mm. 
apart;  ;//,  region  of  stem-initial;  o,  leaf-initial;  £,  stem-initial. 

130.  Longitudinal  section  of  leaf-rudiment  in  radial  longitudinal  section  of  stem. 

X  360. 

131.  Transverse  section  of  two-sided  leaf-initial,  from  a  leaf  with  three  pairs  of 

pinnae. 

132-134.  Serial  sections  (obliquely  sagittal)  through  one  end  of  leaf-initial,  showing 
segments  and  sections.  From  a  leaf  with  four  pairs  of  pinnae. 

135.  Longitudinal  section  of  leaf-initial;  from  a  leaf  with  three  pairs  of  pinnae. 

136.  Longitudinal  section  of  leaf-tip;  no  pinnae. 

137.  Surface  section  of  leaf-tip  with  marginal  initials. 

PLATE  16: 

138.  Longitudinal  section  of  leaf  with  five  pairs  of  pinnae,  showing  loss  of  initial. 

Segments  i  and  2  formed  successively  on  same  side  of  apical  cell. 
X  360. 

139.  Sagittal  section  of  leaf-rudiment  with  three  pairs  of  pinnae,  becoming  circinate. 

Heavy  lines  bound  segments. 


54  STRUCTURE   AND    LIFE-HISTORY   OF   HAY-SCENTED    FERN. 

PLATE  16,  continued: 

140.  Transverse  section  of  rachis  near  apex  of  a  leaf  with  three  pairs  of  pinnae  and 

a  single  initial  cell,  showing  sectioning  of  marginal  cells,  m. 

141.  Ditto;  leaf  with   seventeen  pairs  of  pinnae,  growing  by  a  group  of  marginal 

initials. 

142-143.  Transverse  section  of  rachis  of  a  leaf  with  seven  pairs  of  pinnae,  showing 
cessation  of  division  in  marginal  cells,  in.  Fig.  142  is  between  second 
and  third  pairs  of  pinnae.  X  360. 

144.  Sagittal  section  of  apex  of  a  leaf  with  nine  pairs  of  pinnae,  and  growing  by  a 

group  of  marginal  initials,  m.     X  360. 

145.  Horizontal  section  of  tip  of  pinna;  ;//,  growing  point.     From  a  leaf  with  eleven 

pairs  of  pinnae. 

146.  Transverse  section  of  pinna  near  apex;  in,  marginal  cell. 

147.  Transverse  section  of  leaf  through  a  developing  pinna;  m,  marginal  cell.    From 

same  leaf  as  fig.  146. 
PLATE  17: 

148.  Horizontal  section  of  developing  pinnule;  lobes  and  sinus. 

149.  Horizontal  section  of  teeth  of  pinnule  lobe,  with  developing  veinlets  (shaded). 

150.  Dorsiventral  section  of  developing  lamina. 

151.  Transverse  section  of  leaf  with  rudiment  of  sorus  on  margin;  m,  mother-cell  of 

first  sporangium;  u,  indusium.     X  210. 

152.  Outline  of  pinnule  of  unfolding  leaf.     X  42. 

153.  Surface  of  pinnule  shown  in  fig.  152:  /#,  rudiment  of  stoma. 

154.  Longitudinal  section  of  young  sporangium;  central  cell  just  formed. 

155.  Transverse  section  of  leaf-margin  through  a  mature  sorus;  d,  placenta;  u,  indu- 

sium.    X  210. 

156.  Oblique  longitudinal  section  of  developing  sporangium  with  one  central  cell. 

157.  Longitudinal  section  of  young  sporangium;  stalk  and  wall  segments  cut  off; 

cap  not  yet  formed.     X  360. 

158.  Sagittal  section  of  rudiment  of  sorus;  u,  indusium;  i,  2,  successive  sporangia. 

X  360. 

159-167.  Sections  of  developing  sporangia,  showing  stages  as  follows:  Fig.  159, 
first  cleavage  in  mother-cell;  d,  placenta.  Fig.  160,  three-celled  rudi- 
ment. Fig.  161,  first  tapetal  cell.  Fig.  162,  first  tapetal  layer  com- 
plete (on  right),  leaving  the  archesporial  cell.  A  three-celled  rudiment 
at  left.  Fig.  163,  division  of  the  tapetal  layer.  Fig.  164,  four  arche- 
sporial cells  in  equatorial-plate  stage,  dividing  to  make  eight.  Figs. 
165,  166,  adjacent  sections  of  two  celled  archesporium,  dividing  into 
four.  Fig.  167,  spore  mother-cells;  tapetum  degenerating. 
PLATE  18: 

161-167.  See  above. 

168.  Tetrads,  with  fragment  of  tapetum, 

169.  Paraphysis  arising  from  placenta. 

170.  Sagittal  section  of  sporangium,  showing  the  spore  mother -cells  just  before 

synapsis. 

171-172.  Mature  sporangia,  from  opposite  sides. 
173.  Mature  paraphysis.     X  360. 
174-175.  Surface  views  of  spores. 

176.  Transverse  section  of  stalk  of  sporangium. 

177.  Germinating  spore.     X  360. 

178.  Three-celled  protonema,  short  type. 

179.  Two-celled  protonema.     X  360. 

180.  Three-celled  protonema,  medium  length. 

181.  Four-celled  protonema. 

182.  Protonema  with  short  basal  cells.     X  360. 

183.  Six-celled  protonema. 

184.  Three-celled  protonema.     Long  type. 

185.  Five-celled  protonema  with  two-sided  initial.     X  360. 

186.  Base  of  a  prothallus  without  protonema. 

187.  Protonema  with  two  segments  from  initial.     X  360. 

188.  Five-celled  prothallus  without  protonema.     X  360. 


LIST   OF   ILLUSTRATIONS   AND    EXPLANATION   OF   PLATES.  55 

PLATE  19: 

189.  First  longitudinal  division  in  protonema. 

190.  Seven-celled  protonema  with  two-sided  initial.     X  360. 

191.  Side  view  of  tig.  190. 

192.  Six-celled  protonema;  beginning  of  two-sided  initial. 

193.  Same  as  fig.  192,  showing  length  of  rhizoids. 

194.  Apical  growth  established;  one  antheridium. 

195.  More  advanced  apical  growth,  drawn  from  a  specimen  plasmohzed  in  salt 

solution  in  order  to  show  the  walls. 

196.  Long,  six-celled  protonema  with  two-sided  initial  just  established. 

197.  Protonema  with  irregular  apex. 

198.  Dwarf  male  prothallus.      Westport,  Maryland,   September   25,    1905.      Four 

prothallial  cells,  three  antheridia. 

199.  Normal  male,  becoming  cordate. 

200.  Group  of  marginal  initials  just  established.     X  210. 

PLATE  20: 

201.  Papillar  outgrowth  on  dorsal  surface  of  female  prothallus.     X  210. 

202.  Two-celled  archegonial  rudiment,  d,  in  sagittal  section  of  prothallus.     X  360. 

203.  Upper  surface  of  prothallus;  single  initial  giving  place  to  a  group.     X  210. 

204.  Apical  growth  with  a  group  of  initials;  horizontal  section.     X  360. 

205.  Vertical  transverse  section  of  prothallus,  0.05  mm.  back  of  notch,  /.  <?.,  about 

the  line  i-i  in  fig.  204. 

206.  Three-celled  archegonial  rudiment,  d,  in  sagittal  section  of  prothallus,  cut  along 

the  line  2-2  in  fig.  204.     X  360. 

207.  Three-celled  archegonial  rudiment,  d;  first  cleavage  in  neck-rudiment.     X  360. 

208.  Archegonial  rudiment;  neck  and  central  cell.     X  360. 

209.  Cutting  off  neck  canal-cell.     X  360. 

210.  Longitudinal  section  showing  cleavage  in  neck  cell.     X  360. 

211.  Longitudinal  section  of  young  archegonium  showing  neck  bending  over.    X  360. 

212.  Surface  view  of  neck  of  nearly  mature  archegonium.     X  360. 

213.  Ditto;  young  archegonium.     X  360. 

214.  Archegonial  rudiment,  dy  one  cell.     X  360. 

215.  Longitudinal  section  of  prothallus,  showing  neck  canal  cell  with  two  nuclei. 

X  360. 

216.  Formation  of  ventral  canal-cell.     X  360. 

217.  Axial  cells  of  archegonium  complete;  neck  immature.     X  360. 

218.  Neck  canal-cell  with  three  nuclei. 

219.  Mature  archegonium;  stained  with  iron  haematoxylin.     Ventral  wall  complete. 

X  360. 

220-222.  Transverse  sections  of  mature  neck  at  summit,  middle,  and  base,  respec- 
tively. X  360. 

223.  Egg-cell  ready  for  fecundation. 

224.  Fertilized  egg  in  longitudinal  section  of  archegonium.     Unsuccessful  sperms  in 

mucilage  of  neck.     X  360. 
PLATE  21: 

225.  Longitudinal  section  of  antheridial  rudiment,  one-celled.     X  360. 

226.  Ditto,  two-celled.     X  360. 

227.  Surface  view  of  a  lobe  of  an  old  male  prothallus.     First  division  in  central  cell 

of  antberidium  above.     X  210. 

228.  Ditto;  three-celled  antheridium. 

229.  Side  view  of  antheridium  with  long  basal  cell. 

230.  Antheridium  nearly  mature;  vertical  section.     X  360. 

231.  Rhizoids  of  female  prothallus.     X  210. 

232.  Optical  section  of  three-celled  antheridium;  cleared  in  glycerin.     X  360. 

233.  234.  Octants  of  embryo.     Transverse  sections  of  prothallus,  233  being  15  n 

anterior  to  234;  b,  stem-octant;  d,  rudiment  of  first  leaf;  r,  root-quad- 
rant; ?t,  foot. 

235>  236-  Sagittal  sections  of  embryo  and  calyptra,  25  M  apart;  b,  stem  initial;  d,  mar- 
ginal cell  of  first  leaf;  n,  foot. 

237.  Longitudinal  section  of  old  antheridium. 


56  STRUCTURE   AND    LIFE-HISTORY   OF   HAY-SCENTED    FERN. 

PLATE  22: 

238.  Transverse  section  of  protostele  below  first  leaf-gap.     X  210. 

239.  Transverse   section  o±  stem  through  the  first  leaf-gap,  o.     No  inner  phloem. 

Siphonostelic  structure  occurs  o.i  mm.  higher  up;  tr,  region  of  first  leaf- 
trace.     X  210. 

240.  Transverse  section  of  siphonostele  between  first  and  second  leaves. 

241.  Transverse  section  of  siphonostele  midway  between  third  and  fourth  leaves. 
242-245.  Serial  transverse  sections  of  the  center  of  the  stele  at  the  origin  of  the 

inner  endodermis.     241  to  242  is  60  /*;  242  to  243  is  10  /a;  243   to  244  is 
20  /A;  244  to  545  is  70  p.    All  between  third  and  fourth  leaves.     X  210. 
PLATE  23: 

246.  Sagittal  section  of  young  fern  attached  to  prothallus; ;;?,  stem-initial;  o,  calyptra 

r,  root;  /r,  first  leaf;  u,  prothallus.     X  75. 

247.  Detail  of  transition  from  root  to  stem,  from  same  series  as  fig.  246; ;;/,  anterior; 

r,  posterior;  u,  upper  part. 

248.  Slightly  oblique  transverse  section  of  petiole  of  third  leaf  of  sporeling;  d>  upper 

side.     X2io. 

249.  Glandular  hair  from  leaf  of  adult  plant.     X  43. 

250.  Transverse  section  of  petiole  of  first  leaf,  showing  sectioning  of  marginal  cells. 

Endodermis  dotted;  m,  marginal  cell.     X  360. 

251.  Sinus  of  leaf-margin  of  seedling;  dotted  cells  are  epidermal.     Surface  view  of 

cleared  specimen.     X  350. 

252.  Young  rhizoids  and  tips  of  mature  ones  from  root  of  three-leaved  sporeling  of 

fig.  267.     X  350. 

253.  Optical  section  of  spongy  parenchyma  of  first  leaf  of  sporeling;  cleared  in  gly- 

cerine.    X  350. 

254.  Epidermis  and  developing  stomata  on  sporeling  leaf;  m,  stoma  mother-cells. 

X43- 
PLATE  24: 

255.  Horizontal  section  of  calyptra  (11}  and  embryo  through  root  and  rudiment  of 

first  leaf  (tr}.     X  360. 

256.  Diagrammatic  cross-section  of  sporeling  plant  through  third  leaf-gap;  tr,  petiole 

0,  leaf-gap. 

257.  Diagrammatic  cross-section  of  stele  and  starchy  cortex  of  sporeling  stem  at 

fourth  leaf-gap;  o,  leaf-gap.     X  75. 

258.  Hairs  of  third  leaf  of  sporeling  No.  3;  b,  acicular;  ;;z,  moniliform  ;  n,  glandular. 

X  350. 

259.  First  leaf  of  sporeling  No.  2.     X  5. 

260.  Second  leaf  of  same  plant.     X  5. 

261.  Second  leaf  of  plant  No.  3.     X  5. 

262.  Third  leaf  of  plant  No.  3.     X  5. 

263.  Third  leaf  of  another  plant.     X  5. 

264.  Fourth  leaf  of  plant  No.  3.     X  5. 

265.  Fourth  leaf  of  plant  No.  4.     X  5. 

PLATE  25: 

266.  Lower  epidermis  of  first  leaf  of  sporeling.     X  350. 

267.  Three-leaved  sporeling  (No.  i)  with  portion  of  prothallus  («)  still  attached. 

1,  2,  3,  first,  second,  and  third  leaves. 

268.  Surface  view  of  petiole  of  second  leaf  of  sporeling  (No.  i),  with  stoma. 

269.  Sporeling  stem  with  roots  and  leaves  cut  off.     Drawn  from  nature  by  Miss  M. 

E.  Rogers. 

270.  Forked  stem  of  seedling,     i,  primary  root  leading  up  to  the  original   simple 

stem.     Drawn  from  nature  by  Miss  M.  E.  Rogers. 


Plate   1 


FIG.  i.  Habitat  of  D.  punctilobula,  Massachusetts. 


FIG.  2.  Leaves  as  they  grow. 


Plate  2 


FIG.  3.   Rhizome,  natural  size,  showing  fork,  leaf-bases,  and  leaf-shoots. 

FIG.  4.   Leaf-bud  with  two  unequal  leaf-shoots,  natural  size. 

FIG.  5.  Portion  of  pinna  showing  pinnules,  lobes,  crenations,  sori,  and  hairs.      X  about  10. 


PLATE  3. 


6 


Dorsz 


vi   xi   x   ix 


PLATE  4. 


PLATE  5. 


PLATE  6. 


43 


PLATE?. 


47 


PLATES. 


PLATE  9. 


Plate   10 


68 


69 


PHOTOMICROGRAPHS. 
FIG.  67.   Rhizome,  transverse  section. 
FIG.  68.  Vascular  bundle  of  petiole,  transverse  section. 
FIG.  69.  Rachis  of  leaf,  transverse  section. 


PLATE  11. 


PLATE  12. 


PLATE  13. 


103 


PLATE  14. 


in 


PLATE  15. 


PLATE  16. 


PLATE  17. 


PLATE  20. 


PLATE  21. 


336 


PLATE  22. 


PLATE  23. 


255 


PLATE  25. 


266 


258461 


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UNIVERSITY  OF  CALIFORNIA,  SANTA  CRUZ 

SCIENCE  LIBRARY 


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Series  2477 


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